FS145003 Final report ANNEX 1 v6 Page 1 of 9
ANNEX 1
FINAL REPORT FOR PROJECT FS145003
HISTORICAL DATA- ANALYSIS FOR OBJECTIVE 4
The aim of this study was to compare the various conditions that are found at the traditional
inspection of fattening pigs from indoor fattening and outdoor fattening (free range) pigs in
the study abattoir.
METHODS
Inspection data for pigs slaughtered at one pig-only abattoir in the east of England from
January 2010 to December 2011 were obtained from the Food Standards Agency (FSA).
There were three datasets for each of the batches slaughtered. Data were available for ante-
mortem inspection (AMI) of live animals, post-mortem inspections (PMI) of carcase
inspection and offal inspection.
The batches were categorised as being either from free range systems (fattened outdoors),
or from indoor fattening systems. This was determined by the batch slap mark. This
indicates the farm of origin. The batch slap marks were compared with a list of the
categories of suppliers of pigs obtained from the abattoir management.
The data were transferred to a spread-sheet (Microsoft Excel) and manually inspected for
errors and anomalies; these were excluded from any analysis by replacing the data as
missing. A few of the conditions identified, namely mastitis and orchitis, were of such low
prevalence, with only one or two batches affected, that this was combined with the “other
condition” categories. The data were transferred to a statistical software package (STATA
version 12) for analysis.
The prevalence of each condition in each batch was determined for the datasets by using
the number of times the condition was identified as the numerator and the batch size as the
denominator.
The proportion of batches affected with a condition was determined by recoding the
presence or absence of a condition in a batch as a binary outcome. The two types of
finishing systems were then compared calculating confidence intervals and using a test for
proportions (Z-test). Confounding by batch size and season was investigated by comparing
odds ratios using the Mantel-Haenszel method.
The batches in which the conditions were found were also compared for the two finishing
systems. In this case the mean prevalence in the batches that were found to have the
condition was compared between the systems using a t-test.
Due to the number of analyses performed in the comparisons (n=82) any differences were
considered statistical significant when P<0.0006 using Bonferroni correction.
FS145003 Final report ANNEX 1 v6 Page 2 of 9
RESULTS
The total data available for the analysis contained results from the inspection of 1,220,340
pigs from 7,410 batches from the different rearing and fattening systems
In the analysis period, the mean number of pigs in each batch was 164 and 166 pigs for
indoor and free range fattening systems respectively. There is only slight variation in the
different batch size categories for the different fattening systems (Table A1:1). There was a
degree of seasonal variation in the number of batches of pigs slaughtered, with fewer
batches slaughtered in late spring and in the summer months (Figure A1:1). The proportion
of the batches that were from free range systems was fairly consistent accounting for
approximately a quarter (range 19.5-26.3%) of the batches of pigs slaughtered. Although
batch size and seasonality were considered as possible confounders, when analysed they
had no influence on the associations between the conditions found and the fattening
systems (data not presented).
Table A1:1: Size of the batches of the pigs submitted to slaughter from different fattening systems during 2010 to 2011
Batch size Fattening system Total
Indoor Free Range
n % n % n %
1-50 121 2.1 76 4.6 197 2.66
51-100 652 11.4 247 14.8 899 12.1
101-150 1 366 23.8 270 16.2 1 636 22.1
151-200 1 703 29.7 452 27.2 2 155 29.1
201-250 1 837 32.0 579 34.8 2 416 32.6
251-300 14 0.2 4 0.2 18 0.2
301-350 22 0.4 3 0.2 25 0.3
351-400 13 0.2 9 0.5 22 0.3
401-450 12 0.2 25 1.5 37 0.5
451-500 3 0.1 0 0.0 3 0.0
Total 5 743 100 1 665 100 7 408 100
FS145003 Final report ANNEX 1 v6 Page 3 of 9
Figure A1:1: The number of batches of pigs from each of the different fattening systems that were slaughtered at the abattoir during the analysis period (2010-2011).
Ante-mortem inspection data (Table A1:2).
The proportion of batches in which the various conditions were detected was similar for both
indoor and outdoor fattening systems, except that there was a significant increase in tail bite
and lameness in batches from indoor fattening systems. Indoor fattening systems had
26.4% of batches in which tail bite was identified, compared with 5.9% of free range batches,
and 46.5% had lame pigs compared with 24.7% of free range batches. There were no
differences between the two fattening systems in the mean prevalence of conditions within
the batches where the conditions were present.
392 492 522
402 450 436 472 432
573 541 484
549
140
138 154
117 109 130
137 150
141 134
147
168
0
100
200
300
400
500
600
700
800
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Nu
mb
er o
f B
atch
es S
lau
ghte
red
Month of Slaughter
Indoor Free Range
FS145003 Final report ANNEX 1 v6 Page 4 of 9
Table A1:2: Conditions found at ante-mortem inspection of slaughter pigs from indoor and free range fattening systems (*statistically significant* difference between systems)
Percentage of the batches affected
with the condition (95% C.I.)
Mean prevalence (%) in batches in
which the condition was present (95%
C.I.)
Indoor Free Range Indoor Free Range
Respiratory signs 6.9
(6.1-7.8)
8.3
(5.5-11.1)
0.8
(0.7-0.9)
0.7
(0.1-1.4)
Abscess 10.8
(9.7-11.9)
6.7
(4.2-9.3)
1.2
(0.7-1.8)
0.6
(0.5-0.8)
Dead or Dying 17.0
(15.7-18.3)
14.8
(11.2-18.4)
0.8
(0.8-0.9)
0.6
(0.5-0.7)
Skin lesions 1.3
(0.9-1.7)
0.8
(0.0-1.7)
2.0
(0.03-3.9)
0.9
(0.0-2.6)
Hernia/Ruptures 45.7
(44.0-47.4)
40.6
(35.6-45.6)
1.1
(1.0-1.2)
0.9
(0.8-1.0)
Trauma 5.4
(4.6-6.1)
4.6
(2.5-6.7)
1.0
(0.9-1.3)
0.8
(0.5-1.0)
Joint disease 8.9
(7.9-9.8)
11.8
(8.6-15.1)
0.9
(0.9-1.1)
1.3
(0.04-2.5)
Lumps/Swellings 1.7
(1.2-2.1)
0.5
(0.0-1.3)
1.1
(0.7-1.6)
0.5
(0.2-0.7)
Tail bite *
26.4*
(24.9-27.9)
*5.9
*
(3.5-8.3)
1.4
(1.2-1.6)
0.8
(0.6-1.0)
Neurological signs 0.2
(0.03-0.3)
1.1
(0.02-2.1)
0.5
(0.5-0.6)
0.5
(0.4-0.6)
Lame *46.5
*
(44.8-48.2)
*24.7
*
(20.3-29.1)
1.2
(1.0-1.3)
0.7
(0.6-0.8)
Stress 1.1
(0.1-1.5)
2.7
(1.0-4.3)
2.4
(0.0-5.8)
0.6
(0.5-0.7)
Other 1.3
(0.9-1.7)
1.3
(0.2-2.5)
0.9
(0.5-1.3)
0.6
(0.2-0.9)
*xx.x* (yy.y-zz.z) – statistically significant values are shown in bold text
Post-mortem inspection
The conditions found during carcase inspection were again similar between the two fattening
systems. There were differences in the proportion of batches with carcases showing oedema
and those with hair contamination (Tables A1:3 and A1:4). In indoor fattened pigs 25.7% of
batches had carcases of pigs with oedema compared with 8.1% for free range batches.
FS145003 Final report ANNEX 1 v6 Page 5 of 9
5.9% of free range pig batches had hair contamination compared with 3.9% for batches of
indoor fattened pigs. The prevalence of the conditions in pigs in which the various
conditions were found was again similar for the different fattening systems.
Table A1:3: Pathological conditions found on post-mortem inspection of the carcases of pigs slaughtered from indoor and free range fattening systems (*statistically significant* difference between systems)
Percentage of the batches affected
with the condition (95% C.I.)
Mean prevalence (%) in batches in
which the condition was present (95%
C.I.)
Indoor Free Range Indoor Free Range
Anaemia 5.5
(4.7-6.4)
3.2
(1.8-4.7)
0.8
(0.7-0.8)
0.8
(0.4-1.7)
Jaundice 3.3
(2.7-4.0)
5.4
(3.5-7.3)
0.7
(0.6-0.8)
0.6
(0.5-0.6)
Tumours 0.6
(0.3-0.9)
0.5
(0.1-1.2)
0.6
(0.5-0.7)
0.7
(0.04-1.4)
Oedema *25.7
*
(24.1-27.4)
*8.1
*
(5.8-10.3)
1.1
(1.0-1.2)
1.1
(0.5-1.6)
Poly-arthritis 8.0
(6.9-9.0)
9.7
(7.2-12.2)
0.9
(0.8-1.0)
0.8
(0.6-0.9)
Septicaemia 10.7
(9.5-11.9)
10.1
(7.6-12.6)
0.7
(0.7-0.8)
0.8
(0.6-0.9)
Pyaemia 75.5
(73.9-77.2)
71.1
(67.3-74.9)
1.5
(1.4-1.6)
1.1
(1.0-1.3)
Uraemia 1.0
(0.7-1.4)
1.1
(0.2-1.9)
0.6
(0.5-0.7)
0.6
(0.4-0.8)
Other Conditions 8.4
(7.3-9.4)
12.8
(10.0-15.5)
1.9
(0.8-0.9)
1.2
(0.7-1.6)
*xx.x* (yy.y-zz.z) – statistically significant values are shown in bold text
FS145003 Final report ANNEX 1 v6 Page 6 of 9
Table A1:4: Processing faults found at post-mortem inspection of slaughtered pigs from indoor and free range rearing systems (*statistically significant* difference between systems)
Percentage of the batches affected
with the condition (95% C.I.)
Mean prevalence (%) in batches in
which the condition was present (95%
C.I.)
Indoor Free Range Indoor Free Range
Badly Bled 1.3
(0.8-1.7)
1.6
(0.6-2.7)
1.0
(0.3-1.6)
0.6
(0.4-0.9)
Machine Damage 2.1
(1.6-2.7)
3.4
(1.9-4.9)
3.3
(1.2-5.4)
7.4
(1.3-16.0)
Blood Splash 0.9
(0.7-1.2)
0.4
(0.1-0.7)
0.7
(0.6-0.8)
1.0
(0.5-1.5)
Bile Contamination 93.6
(92.9-94.2)
92.7
(91.4-94.0)
4.2
(4.1-4.2)
4.1
(4.0-4.3)
Faecal Contamination 75.4
(74.3-76.5)
72.6
(70.4-74.8)
2.9
(2.8-3.0)
2.9
(2.7-3.0)
Grease Contamination 3.6
(3.1-4.1)
3.5
(2.6-4.4)
0.8
(0.7-0.9)
0.9
(0.8-1.1)
Hair Contamination *3.9
*
(3.4-4.4)
*5.9
*
(4.8-7.1)
0.8
(0.7-1.0)
1.0
(0.8-1.1)
Other 0.2
(0.1-0.3)
0.2
(0.03-0.4)
16.4
(0.0-38.5)
0.6
(0.0-1.8)
*xx.x* (yy.y-zz.z) – statistically significant values are shown in bold text
The comparison of the frequency of the pathological conditions found at post-mortem
inspection of offal for the different fattening systems (Table A1:5) revealed that milk spot liver
occurred in more batches of free range fattened pigs compared with indoor fattened ones
(54.8% of batches affected compared with 23.4%). By contrast, pericarditis was found to
occur in more batches of indoor fattened pigs than free range fattened pigs (60.6% of
batches compared with 53.5%). The proportion of batches with other conditions was similar
between the two fattening systems.
When the prevalence of conditions, found at offal inspection in batches where the conditions
occurred, were compared it was found that kidney pathology was significantly higher in
indoor fattened pigs, whereas the within batch mean prevalence of hepatitis, milk spot liver,
peritonitis, pneumonia and other pathology was higher in free range fattened pigs. These
differences were on the whole small except for milk spot liver in which a large difference was
found. There was a mean of 21.1% of pigs affected in free range fattened pigs compared
with 5.9% in indoor fattened pigs.
FS145003 Final report ANNEX 1 v6 Page 7 of 9
Table A1:5: Pathological conditions found during post-mortem inspection of offal from slaughter pigs from indoor and free range fattening systems (*statistically significant* difference between systems)
Percentage of the batches affected
with the condition (95% C.I.)
Mean prevalence (%) in batches in
which the condition was present
(95% C.I.)
Indoor Free Range Indoor Free Range
Abscess 23.7
(22.6-24.8)
24.2
(22.1-26.3)
2.5
(2.3-2.7)
3.3
(2.6-4.0)
Enteritis 24.3
(23.2-25.4)
24.3
(22.3-26.4)
1.7
(1.5-1.8)
1.8
(1.7-2.0)
Endocarditis 5.2
(4.6-5.8)
3.5
(2.6-4.4)
1.0
(0.9-1.1)
0.8
(0.6-0.9)
Hepatitis 35.8
(34.6-37.1)
34.1
(31.8-36.3)
*2.2
*
(2.1-2.4)
*3.1
*
(2.5-3.6)
Kidney Pathology 95.2
(94.7-95.8)
93.8
(92.6-94.9)
*7.2
(7.1-7.4)
*6.7
*
(6.4-6.9)
Milk Spot *23.4
*
(22.3-24.5)
*54.8
*
(52.4-57.2)
*5.9
*
(5.2-6.6)
*21.1
*
(19.5-22.7)
Pericarditis *60.6
*
(59.4-61.9)
*53.5
*
(51.1-55.9)
2.0
(1.9-2.1)
2.0
(1.9-2.2)
Peritonitis 57.7
(56.4-58.9)
58.6
(56.3-61.0)
*1.8
*
(1.7-1.8)
*2.4
*
(2.1-2.6)
Pleurisy 39.9
(38.6-41.2)
38.4
(36.0-40.7)
2.3
(2.2-2.4)
2.6
(2.4-2.8)
Pneumonia 86.6
(85.8-87.5)
88.9
(87.4-90.5)
*8.6
*
(8.4-8.9)
*10.8
*
(10.2-11.4)
Other Pathology 78.2
(77.1-79.3)
76.2
(74.2-78.3)
*4.9
*
(4.8-5.1)
*6.0
*
(5.6-6.4)
*xx.x* (yy.y-zz.z) – statistically significant values are shown in bold text
FS145003 Final report ANNEX 1 v6 Page 8 of 9
DISCUSSION
The data obtained were both extensive, covering all pigs slaughtered over a two year period
from the slaughterhouse, and of high quality with little data being censored; over 99.9% of
the data were used in the analysis.
The possibility exists that conditions detected could have been misclassified or detected with
a different degree of accuracy depending on who was performing the inspection. This is
unlikely to have introduced any significant bias into the analysis as this would likely to have
been non-differential, so equal in the two fattening systems compared.
The classification of the batches of pigs to the type of fattening system was likely to be
accurate as the slaughterhouse had good records of the provenance of pigs; this was in their
commercial interests, as free range pigs command a premium.
The study only involved the inspection data from one abattoir, which is likely to have only
obtained pigs from a discrete geographical region. Potentially this means that the results of
the analysis cannot be generalised to pigs slaughtered in other regions, although most of the
outdoor fattened pigs are produced in the east of England.
The comparison of the different fattening systems revealed that the prevalence of conditions
found at inspection were quite similar between the two. The finding of a higher frequency of
batches with tail bite and lameness at ante-mortem inspection in the indoor fattening
systems was not surprising. Tail biting in pigs is associated with poorer environmental
enrichment and lameness can be associated with poor flooring, so both of these conditions
are associated with housing. When it occurred, however the within batch prevalence was
not statistically significantly different between the two management systems.
Of interest was the very much higher proportion of batches of pigs with oedema in indoor
fattening systems. Oedema can have many causes including liver pathology, cardiac
pathology and kidney pathology none of these were excessively elevated in the comparisons
to explain this large difference. Again, the numbers of pigs affected within batches where
the condition was found were similar between the two fattening systems.
Milk spot liver occurred more frequently in free range fattened pigs, with it being detected in
more than twice the number of batches of free range pigs compared with indoor fattened
ones. In addition, more than a fifth of livers from pigs in which the condition was found were
rejected from free range fattened pigs. Again, this is not unexpected as milk spot liver is
caused by the migration of the larvae of the intestine worm Ascaris suum through the liver.
This migration causes inflammation and haemorrhage which is subsequently repaired by
fibrous material leading to white areas in the liver, the milk spots. The eggs of this worm are
very resistant and so may persist for very many years in the environment, and so are more
likely in pigs reared and fattened outdoors.
Pericarditis was found to occur in more batches of indoor pigs, although this difference is
unlikely to be biologically significant.
FS145003 Final report ANNEX 1 v6 Page 9 of 9
CONCLUSION
In conclusion, the prevalence of conditions detected on inspection of pigs submitted to
slaughter from different fattening systems, are, on the whole, quite similar. Most of the
differences can be predicted from the housing and fattening systems used and knowledge
about the influence this has on the occurrence of diseases. This similarity would suggest
that whatever inspection system was in place, it would be likely be equally effective for pigs
from both types of management systems.
FS145003 Final report ANNEX 2 v6 Page 1 of 15
ANNEX 2
FINAL REPORT FOR PROJECT FS145003
ANALYSIS OF CONDITIONS FOUND AT POST-MORTEM INSPECTION FOR
OBJECTIVES 1, 2, AND 3
The aim of these studies was to establish a baseline of the frequency and types of
pathological conditions that can be expected to be identified when using visual-only
inspection in fattening pigs from non-controlled housing conditions; to do the same when
using traditional inspection; and, to compare the baseline values of the frequency and type
of conditions found using the two inspection methods.
MATERIAL AND METHODS
Sample size
The sample size for the study was estimated, in R http://www.r_project.org, a priori as
follows:
It is estimated that approximately 120 commercial herds supply abattoirs with pigs finished
outdoors in the United Kingdom (UK), with an average of 15 batches a year and
approximately 220 pigs per batch (Quality Meat Scotland, personnel communication).
Virtually all outdoor pig finishing units are located in England. The distribution of the
frequency of occurrence of various pathologies is unlikely to be uniform across farms or
batches. For low prevalence conditions it has been assumed that the minimum farm level
prevalence is 25% with at least 0.1% of batches affected. All pigs from each batch included
in the trial would be inspected; therefore within batch sample size calculations are irrelevant.
To allow an estimate of overall pig prevalence (for each sampling period) with a precision of
2% to be made with 95% certainty, assuming the worst case scenario (i.e. a true prevalence
of 50%), then a total of 10 different farms would need to be sampled, with an aim to include
five batches per farm, so that 50 batches in total will be inspected for the study. This would
lead to a total of 11,000 pigs inspected.
Recording of data
During traditional inspection Meat Hygiene Inspectors (MHIs) recorded all conditions found
on a touch screen system. This information was then transferred to the plant records from
where it can be printed out for each batch (identified by the individual slap mark). Data were
collected from the FSA records and transferred, by double entry, to a Microsoft Office Excel
Worksheet by project personnel.
The data for the conditions found at the visual-only inspection point were recorded by MHIs
on a recording sheet that mirrored the FSA records. Identification was again at the batch
level i.e. by the individual slap mark. These data were also double entered on a Microsoft
Office Excel Worksheet by project personnel.
All data collected during the trial were stored in the Microsoft Office Excel Worksheet. Each
batch was identified by a unique code (id), date of slaughter, week of slaughter,
FS145003 Final report ANNEX 2 v6 Page 2 of 15
slaughterhouse, slap mark, number of pigs slaughtered, number of pigs inspected and all
conditions identified by MHIs by both methods (traditional and visual-only). The number of
pigs inspected was equal to the number slaughtered unless logistical issues occurred during
the recording. For example, if there was no recording available for traditional inspection then
no visual-only inspection was recorded until the system was resolved. This was to ensure
that the carcasses inspected by both inspection methods were the same.
The conditions were initially stored exactly as observed in the abattoir for recording purposes
during the trial. Conditions were then regrouped into categories ready for the statistical
analyses. These groups, or categories, were created following the same criteria used for the
historical analysis of frequency and types of conditions identified by post-mortem inspection
for fattening pigs from controlled and non controlled housing conditions (see Annex 1;
Objective 4).
Statistical analysis
All analyses were performed with R version 2.12.1 from R Foundation for Statistical
Computing. http://www.r_project.org
The data used for the purpose of this study consist of paired observations, from the same
sample population. For all carcasses from the same batch (a group of pigs coming from the
same farm) both traditional and visual inspection methods were applied to the same
carcasses. The frequency of a condition was recorded as the number seen per batch. The
number of pigs in each batch was also provided. The statistical methods used account for
this.
There was only one study abattoir so it was not possible to test if the abattoir influences the
results. The trial took place in five separate weeks, between the end of November 2011 and
the middle of March 2012. This could be considered as the same season; nevertheless the
effect of season was investigated at the level of week.
The number of animals affected, and the frequency (%), or prevalence, of each condition
found by each inspection method was estimated, and its 95% confidence intervals (C.I.)
were calculated. The C.I was calculated for the within batch prevalence using a t-test
approximation to the normal distribution. The distributions of the counts for each condition
were plotted to see if they follow a normal distribution. This was done separately for the two
methods of inspection. The proportion of each condition in each batch for the two inspection
methods was plotted to see if there was an association between the two methods. The
points were coloured by slap mark to visualise if slap mark (farm of origin) might affect the
results. Bland Altman plots were used to analyse the agreement between the two inspection
methods (the Bland Altman plot or difference plot is a method of data plotting used to
analyse the agreement between two different assays/methods).
For those conditions that followed a normal distribution a paired t-test was applied to see if
there were differences between the two proportions and a Pearson‟s correlation test to see if
there was a correlation between the two proportions. The season effect was investigated
using linear models.
The conditions that did not follow a normal distribution were categorised as „absence‟ or
„presence‟ of the condition for each batch. The data were analysed as a binary variable. The
FS145003 Final report ANNEX 2 v6 Page 3 of 15
McNemar test was used to see if there were differences between the two methods.
Sensitivity and specificity were estimated for the visual-only method using the traditional
inspection as the standard because the traditional inspection method is recognised and
currently applied in the UK for post-mortem inspection of pigs in abattoirs. The Kappa test
was also estimated to analyse the agreement between the two methods.
Due to the number of analyses performed in the comparisons (n=20) any differences were
considered statistical significant when P<0.00256, using Bonferroni correction.
For the purposes of this report it is, therefore, considered that any estimate is statistically significant if it has a p value < 0.00256.
RESULTS
Farms, batches and carcasses included in the trial:
A total of 62 batches and 11, 086 carcasses were inspected for the purpose of this study.
Twelve different farms were included. Different numbers of batches have been inspected
from each farm during the trial (Table A2:1).
Table A2:1: Summary statistics for the numbers of batches inspected per farm over the study period
Number of batches
inspected per farm
Min Mode Median Mean Max
1
4
4
5.2
19
Descriptive analysis of conditions
Original conditions from the trial are described in the “FSA coding of conditions” column
(Table A2:2). There were 179 different types of conditions found by traditional inspection
recorded and 179 conditions found by visual-only inspection recorded. They were the same
179 conditions (e.g. “bile contamination in trotter found by visual-only inspection” and “bile
contamination in trotter found by traditional inspection”). These conditions were regrouped
into 20 categories, or groups, of conditions. This differs from the preliminary report where 19
groups of conditions were identified. „Pathology in the pluck‟ was previously included in
„other‟ conditions. However, on further examination of the data it has been considered
separately due to the prevalence and the differences in prevalence between traditional and
visual inspection (1.6% and 4.7%) of the condition. The descriptive analysis of the data is
provided below (Table A2:2 and Figure A2:1).
FS145003 Final report ANNEX 2 v6 Page 4 of 15
Figure A2:1: Preliminary descriptive analysis of the frequency (%) of the conditions found in pigs from non-controlled housing conditions at post-mortem meat inspection by the two inspection methods.
Table A2:2: Descriptive analysis of the frequency (number [N]; percentage [%] and 95% confidence intervals [C.I.]) of the conditions found in pigs from non-controlled housing conditions at post-mortem meat inspection by the two inspection methods
Conditions in whole carcasses and offal
FSA coding of conditions Visual-only inspection Traditional inspection
N %
95% C.I.
N %
95% C.I.
Generalised Conditions
Suspect pyaemia, Suspect
fever/septicaemia,
Oedema/Emaciation, Anaemia
12 0.1
0.02 – 0.20
55 0.5
0.16 – 0.83
Abscess Abscess in any part of carcase or offal 172 1.6
1.14 – 1.96
235 2.1
1.56 – 2.68
Hepatic Pathology Hepatopathy, Hepatitis/Cirrhosis,
Jaundice
27 0.2
0.92 – 0.40
88 0.8
0.39 – 1.20
Milk Spot Milk Spot 263 2.4
1.33 – 3.41
601 5.4
3.52 – 7.32
Renal Pathology Kidney lesions, kidney pathology,
suspect uraemia
448 4.0
3.28 – 4.80
798 7.2
5.87 – 8.52
Endocarditis Endocarditis 0 0 21 0.2
0.05 – 0.33
Pericarditis Pericarditis 195 1.8
1.30 – 2.22
184 1.7
1.6 – 2.06
Pneumonia Pneumonia with abscess, pneumonia
without abscess
588 5.3
3.57 – 7.04
762 6.9
4.97 – 8.78
Pleurisy Pleurisy 494 4.5
3.30 – 5.61
369 3.3
2.38 – 4.27
FS145003 Final report ANNEX 2 v6 Page 5 of 15
Conditions in whole carcasses and offal
FSA coding of conditions Visual-only inspection Traditional inspection
N %
95% C.I.
N %
95% C.I.
Enteritis Enteritis, colitis, Pathology in the guts 22 0.2
0.97 – 0.33
123 1.1
0.75 – 1.47
Peritonitis Peritonitis 231 2.1
1.38 – 2.79
221 2.0
1.35 – 2.63
Skin Pathology Skin conditions, dermatitis, erysipelas-
like lesions, bruising
107 1.0
0.65 – 1.28
108 1.0
0.75 – 1.20
Joint Pathology Arthritis 275 2.5
1.57 – 3.39
196 1.8
1.18 – 2.36
Pluck Pathology Pathology in the pluck 181 1.6
0.82 – 2.44
524 4.7
3.47 – 5.98
Other Conditions Other conditions 52 0.5
0.26 – 0.68
127 1.1
0.52 – 1.77
Bile Contamination Bile contamination in any part of
carcase/offal
516 4.7
4.00 – 5.30
574 5.2
4.39 – 5.97
Faecal Contamination Faecal contamination in any part of
carcase/offal
353 3.2
2.16 – 4.21
545 4.9
3.53 – 6.30
Grease Contamination Grease contamination in any part of
carcase/offal
58 0.5
0.30 – 0.75
49 0.4
0.16 – 0.73
Hair Contamination Hair contamination in any part of
carcase/offal
1362 12.3
9.83 – 14.75
419 3.8
1.20 – 6.36
Other Processing Faults Machine Damage, Over scald, Blood
splash, Other processing faults
31 0.3
0.05 – 0.51
23 0.2
0.04 – 0.37
Distributions of the counts for each condition
The distribution of the counts for each condition found by both inspection methods suggest
that generalised condition (Figure A2:2), hepatic pathology (Figure A2:3), endocarditis
(Figure A2:4) and other processing faults (Figure A2:5) do not seem to follow the normal
distribution and so they were categorised into presence or absence of the condition. It is only
possible to apply the paired t-test to compare the frequency of detection of conditions by
both inspection methods when the data follow the normal distribution (Gaussian curve). An
alternative test was used for the four conditions above that did not follow the normal
distribution. The rest of the conditions seem to fulfil the assumption of normal distribution.
FS145003 Final report ANNEX 2 v6 Page 6 of 15
Figure A2:2: Distribution of batch counts for the generalised condition for each inspection method
Figure A2:3: Distribution of batch counts for hepatic pathology for each inspection method
FS145003 Final report ANNEX 2 v6 Page 7 of 15
Figure A2:4: Distribution of batch counts for endocarditis for each inspection method
Figure A2:5: Distribution of batch counts for other processing faults for each inspection method
Plots of the proportions for each condition
From the plots of the proportion of each condition found by the two inspection methods for
each of the batches, the four conditions previously mentioned (generalised condition (Figure
FS145003 Final report ANNEX 2 v6 Page 8 of 15
A2:6), hepatic pathology (Figure A2:7), endocarditis (Figure A2:8) and other processing
faults (Figure A2:9)) again do not seem to show any association between the two inspection
methods. For the rest of the conditions it seems that the slap mark does not influence the
results i.e. no clusters are visually apparent.
Figure A2:6: Plot of the proportion of generalised conditions for the traditional versus visual inspection. The colours represent the slap mark.
Figure A2:7: Plot of the proportion of hepatic pathology for the traditional versus visual inspection. The colours represent the slap mark.
FS145003 Final report ANNEX 2 v6 Page 9 of 15
Figure A2:8: Plot of the proportion of endocarditis for the traditional versus visual inspection. The colours represent the slap mark.
Figure A2:9: Plot of the proportion of other processing faults for the traditional versus visual inspection. The colours represent the slap mark.
Paired t test and Pearson’s correlation test for conditions with an observed
normal distribution
There were statistically significant differences between traditional (considered the standard
method, as traditional inspection is accepted and applied for post-mortem inspection in
abattoirs in the UK) and visual inspection methods for the majority of the conditions analysed
FS145003 Final report ANNEX 2 v6 Page 10 of 15
(Table A2:3). There were no statistical differences for pericarditis, peritonitis, skin pathology,
joint pathology and grease contamination.
Table A2:3: Summary of the mean of the differences and its 95% confidence interval (C.I.) for the mean of the difference between the percentage of detection of conditions/contaminations between traditional (as the „gold‟ standard) and visual inspection methods – conditions with statistically significant p values shown in bold text
Condition Mean of the difference
(traditional – visual) %
95% C.I. for mean
difference %
P value
Lower
Level
Upper
Level
Abscess 0.67 0.09 1.25 0.02
Milk spots 3.21 1.51 4.91 <0.001
Renal Pathology 3.09 1.82 4.37 <0.001
Pericarditis 0.07 -0.53 0.67 0.82
Pneumonia 1.87 0.40 3.34 0.01
Pleurisy -1.12 -2.16 -0.08 0.04
Enteritis 0.99 0.61 1.37 <0.001
Peritonitis 0.06 -0.73 0.84 0.89
Skin pathology 0.05 -0.24 0.34 0.73
Joint pathology -0.84 -1.86 0.18 0.10
Pluck pathology 3.02 1.88 4.15 <0.001
Bile contamination 0.86 0.08 1.65 0.03
Faecal contamination 1.62 0.80 2.44 <0.001
Grease contamination -0.17 -0.52 0.17 0.31
Hair contamination -8.21 -10.79 -5.63 <0.001
Other conditions 0.75 0.07 1.43 0.03
The highest means of the differences between traditional and visual inspection, where more
affected carcasses were found by the traditional method than the visual method, are for the
FS145003 Final report ANNEX 2 v6 Page 11 of 15
following conditions: milk spots (3.21%, 95% C.I. 1.51 – 4.91), renal pathology (3.09%, 95%
C.I. 1.82 – 4.37), pluck pathology (3.02%, 95% C.I. 1.88 – 4.15), and faecal contamination
(1.62%, 95% C.I. 0.80 – 2.44). The highest mean difference however, is for hair
contamination (8.21%, 95% C.I. 5.63 – 10.79). For this condition more affected carcasses
were found with the visual inspection method than the traditional method.
For the majority of the conditions there is a statistically significant correlation between the
findings by the different inspection methods (Table A2:4). The strongest correlations are for
the faecal contamination (0.81, 95% C.I. 0.70 – 0.88) and pneumonia (0.71, 95% C.I. 0.56 –
0.82). If two variables (in our case both types of inspection methods) show strong correlation
then they are variables that tend to vary together, they change in similar way; i.e. when
traditional inspection detects a high number of one particular condition, the visual-only
inspection will also detect a high number of that condition.
Table A2:4: Correlation estimate, 95% confidence interval (C.I.) and p value for the condition analysed – conditions with statistically significant p values shown in bold text
Condition (traditional-visual) Correlation estimate (95%C.I.) P value
Abscess 0.57
(0.38 - 0.72)
<0.001
Milk spots 0.57
(0.38 - 0.72)
<0.001
Renal Pathology 0.46
(0.24 - 0.64)
<0.001
Pericarditis 0.16
(-0.09 - 0.39)
0.215
Pneumonia 0.71
(0.56 - 0.82)
<0.001
Pleurisy 0.54
(0.34 - 0.70)
<0.001
Enteritis 0.29
(0.05 - 0.51)
0.021
Peritonitis 0.32
(0.08 - 0.53)
0.010
Skin pathology 0.53
(0.32 - 0.69)
<0.001
Joint pathology 0.53
(0.32 - 0.69)
<0.001
FS145003 Final report ANNEX 2 v6 Page 12 of 15
Condition (traditional-visual) Correlation estimate (95%C.I.) P value
Bile contamination 0.48
(0.26 - 0.65)
<0.001
Faecal contamination 0.81
(0.70 - 0.88)
<0.001
Grease contamination 0.23
(-0.02 - 0.46)
0.069
Hair contamination 0.47
(0.25 - 0.64)
<0.001
Pluck pathology 0.59
(0.40 - 0.73)
<0.001
Other conditions 0.15
(-0.10 - 0.39)
0.244
McNemar test for conditions with an observed abnormal distribution
There was a statistically significant difference between the two inspection methods for two of
the four conditions where a non-normal distribution was observed (Table A2:5).
If the traditional inspection method is assumed to be the „gold‟ standard method, there is not
a good agreement between the two inspection methods for these conditions as the kappa
values were low for all of them. This is mainly because the sensitivity was low for all of them
(Table A2:6).
Table A2:5: MacNemar results for the categorised conditions
Condition P value
Generalised conditions <0.001
Hepatic pathology 0.045
Endocarditis 0.0015
Other processing faults 0.606
FS145003 Final report ANNEX 2 v6 Page 13 of 15
Table A2:6: Sensitivity (SE), specificity (SP), 95% confidence interval (C.I.), Youden‟s J statistic, Kappa value and the interpretation for the conditions analysed as binary variables.
Condition SE (95%C.I.) SP (95% C.I.) Youden’s J
statistic
Kappa
value
Interpretation
of kappa value
Generalised
conditions 26.1
(11.1 - 45.7)
100
(88.9 - 100)
0.2608 0.31 Low association
Hepatic
pathology 8.7
(1.5 - 29.5)
76.9
(60.3 - 88.3)
-0.1441 -0.16 Low association
Endocarditis 0
(0.0 - 30.1)
100
(91.1 - 100)
0 0 Low association
Other
processing
faults
40
(13.7 - 72.6)
82.7
(69.2 - 91.3)
0.227 0.20 Low association
No seasonal effect was found and the Bland Altman plots (not presented here) for the
conditions analysed suggest that linear regression does not apply to these data due to the
dispersion of the data.
FS145003 Final report ANNEX 2 v6 Page 14 of 15
DISCUSSION
The trial was carried out in one study abattoir. For logistical reasons a second abattoir in
south west of UK was not included. Conditions in pigs might be different depending on the
locations of the farms of origin. This may particularly be the case for abattoirs in the south
west of England, where bovine TB is present and outdoor pigs might be at a higher risk of
contact with TB than indoor pigs. However, most pig farms are located in the east of England
and due to the large number of outdoor pigs processed in the study abattoir we have
covered different areas of production in the UK. The study farms were located in the East of
England (in Norfolk and Suffolk) and in the South West (in Wiltshire). It will be unlikely that
we can generalise the finding to the whole of the UK unless we do further research into the
coverage of the study population achieved. As batches of carcasses included in the trial
have been identified (by the slap mark which identifies the farm of origin) and we know the
spatial location of the study farms, we could do some further studies of geographical
coverage of the study population and the need to include different areas in future studies, if
spatial location data for the denominator population were available. Industry experts have,
however, indicated that such data are “not easily found.”
The fact that the trial was carried out in only one abattoir might have biased the result by the
layout of the slaughter line. In the opinion of one of the authors, with extensive experience in
various abattoirs in the UK, the layout is not that different to the majority of the abattoirs in
UK, if not better. The effect of any such bias is, therefore, considered to be minimal.
The trial took place in five separate weeks, between the end of November 2011 and the
middle of March 2012. Season does not appear to have any effect on the difference
estimates. This is not unexpected as the weeks included in the trial were all during the winter
and a seasonal effect in the conditions was very unlikely to be present. If different seasons
were included in the trial some effect might potentially be expected; however, no such effect
of seasonality was found in the historical analysis for Objective 4 (Annex 1). The main
reason for the selection of winter season for the set up of the trial was the fact that the
presence of certain conditions, such as respiratory conditions (pneumonia, pleurisy), are
believed to be higher during the winter months. The trial was not designed to compare the
seasonality of conditions, but to study the effect of both post-mortem inspections when those
conditions peak.
When we compared visual-only inspection with traditional inspection it can be seen that
there are only slight differences between the frequencies with which each condition was
found. It is possible and not unexpected that conditions may be missed by visual-only
inspection. Although these differences are statistical significant they are less than 3.5% for
the majority of the conditions. This implies that at batch level there is not a biologically
significant difference between visual-only and traditional inspection, as the actual number of
carcases with these conditions that were missed (milk spot, renal pathology, and pluck
pathology) was very low. The detection of these conditions by visual-only inspection might
be improved by the alteration of the current layout of the slaughter line to maximise visual
access to all parts of carcases and offal (Objective 5; Annex 5). The majority of conditions
where traditional inspection exceeded visual-only inspection are conditions in offal; access to
the whole offal was substantially reduced by the visual-only inspection method. If access is
improved to all parts, then it will increase the ability to find these conditions. The same could
FS145003 Final report ANNEX 2 v6 Page 15 of 15
be said for conditions located in the back of the carcase and any contamination affecting the
rear of carcase that is not accessible for visual-only inspection. However, endocarditis will
only be detected by incision of the heart.
For those conditions with a statistically significant correlation between the findings by the
different inspection methods, such as faecal contamination and pneumonia, with an increase
in the prevalence of these conditions the difference between visual and traditional inspection
will remain the same.
For the purpose of this study we have assumed that the traditional inspection method is the
gold standard method (as it is currently accepted and applied in all abattoirs in UK for the
purpose of hygiene inspection). Ideally, a detailed post-inspection examination of carcases
and offal would be undertaken to establish the validity of this assumption.
CONCLUSION
We have found statistically significant differences between the number of carcasses found to
be affected by several conditions when examined by traditional and visual-only inspection.
For the majority of these conditions, traditional inspection finds more cases. Nevertheless,
the difference estimates are low, mostly under 3% and the biological significance is minimal
to negligible. Differences in conditions detected by both methods are very small and the
impact of those differences on the public health is expected to be negligible to very low
(Annex 4 Objective 8).
Some of the differences might be resolved with alterations to the abattoir line to allow a
better and full visual access to all parts of carcase and offal during the post-mortem
inspection. For further discussion and recommendations about implementation see Annex 5
Objective 5).
FS145003 Final report ANNEX 3 v6 Page 1 of 24
ANNEX 3
FINAL REPORT FOR PROJECT FS145003
METHODS AND ANALYSIS FOR MICROBIOLOGICAL INVESTIGATIONS -
OBJECTIVES 6 & 7
The aims of this study are:
to establish the baseline of microbial cross contamination (total aerobic plate
count, Enterobacteriaceae count, and Salmonella isolation) after visual-only post-
mortem inspection and after traditional post-mortem inspection of fattening pigs
from non-controlled housing conditions;
to identify any difference in the risk of cross contamination in carcases visually
inspected compared to those traditionally inspected through total aerobic plate
count, Enterobacteriaceae count, and Salmonella spp. isolation;
to establish the baseline of microbial cross contamination with Yersinia spp. after visual-only post-mortem and after traditional post-mortem inspection of fattening pigs from non-controlled housing conditions.
to identify any difference in the risk of cross contamination in carcases visually inspected compared to those traditionally inspected through Yersinia spp isolation.
MATERIALS AND METHODS
Sample size
The sample size for the study was estimated a priori for each of the different elements to
be investigated. Sample sizes were calculated with R. http://www.r_project.org.
1. Sample size for detection of total aerobic plate count and Enterobacteriaceae count
Due to the variation of microbiological contamination across abattoirs (Zwefel et al.,
2005) we had to make some assumptions in order to calculate the appropriate sample
size for this study. We assumed the worst scenario where 50% of carcases have
evidence of cross-contamination with presence of Enterobacteriaceae and we aimed to
detect a difference of at least 10 percentage points in the proportion of carcases
presented with microbiological contamination between traditional and visual inspection,
with a power of 80% and a significance level of 95%. The estimated sample size was
412 swabs for each group (carcases traditionally inspected and carcases visually
inspected) with 824 swabs in total.
FS145003 Final report ANNEX 3 v6 Page 2 of 24
2. Sample size for isolation of Salmonella spp.
The baseline prevalence of Salmonella in carcases varies across abattoirs but it remains
low (0% to 9.64% (Unpublished data BPEX/FSA WP4); 13.5% (95% C.I. 9.9 – 18.1%)
from surface swabbing of carcases in the UK during the EU survey carried out in 2007
(Anonymous, 2008)). Assuming a baseline prevalence of 15% of the carcases presented
with Salmonella and still aiming to detect a difference of 10 percentage points, with a
power of 80% and a significance level of 95%, we need to process 160 swabs for each
group (carcases traditionally inspected and carcases visually inspected), 320 swabs in
total.
A total 824 samples would suffice to cover all microbial counts and isolation. The same
swabs will be used to test for the total aerobic plate count, Enterobacteriaceae, and
Salmonella.
3. Sample size for Yersinia spp.
Yersinia is not included in the compulsory microbiological checks in the EU and,
therefore there is uncertainty regarding Yersinia prevalence in carcases in the United
Kingdom (UK). It is believed that the prevalence of Yersinia spp., in carcases in the UK,
is as low if not lower than the prevalence of Salmonella (EFSA, 2012).
The sample size for this study was estimated based on the same assumption used for
Salmonella spp. Assuming a baseline prevalence of 15% of the carcases presented with
Salmonella and still aiming to detect a difference of 10 percentage points, with a power
of 80% and a significance level of 95%, we need to process 160 swabs for each group
(carcases traditionally inspected and carcases visually inspected), 320 swabs in total.
This is less than half of the total number of swabs to be collected in the trial.
Sample collection
Swabs were collected after traditional inspection and visual-only inspection of batches of
fattening pigs from non controlled housing conditions slaughtered in the study premises.
Swabs had to be collected and sent to the diagnostic laboratory (Epidemiology Research
Unit [ERU], Inverness) before 11 am every day during the trial, so batches included in
the study for collection of conditions found at traditional inspection and at visual-only
inspection (but expected to be slaughtered after 10 am that day were not included in the
sampling frame, to avoid any delay with the transport of samples to the laboratory.
Swabs were collected in five separate weeks, within the period 28th November 2011 to
16th March 2012. Swabs were collected every day from Monday to Friday during those
weeks when logistically possible. There were only three days of sampling during the first
week due to industrial action and issues with the courier.
The aim for the study was to collect approximately 200 swabs weekly, 40 swabs daily
(20 swabs after traditional inspection and 20 swabs after visual-only inspection) over
four weeks of the full trial to achieve the sample size required for the Enterobacteriaceae
FS145003 Final report ANNEX 3 v6 Page 3 of 24
count (n=800). One in every two swabs would then be selected with a random
systematic method, every day once the samples arrived at the laboratory to be used for
the isolation of Yersinia (n= 400).
In the pilot study week (week 1) 160 samples were collected and processed for Yersinia
spp. only, to study the capacity of the laboratory to process the samples for the rest of
the trial. These samples were not processed for total aerobic plate count,
Enterobacteriaceae count or Salmonella spp. isolation.
In the first two weeks of the full trial (weeks 2 & 3), samples were taken at the abattoir
after traditional inspection with a different pattern, due to logistical issues; however, this
is not expected to affect the analysis. One in every two swabs was selected on arrival at
the laboratory, as described above, to be used for the isolation of Yersinia (n= 199). All
samples were processed for total aerobic plate count, Enterobacteriaceae count and
Salmonella spp. isolation.
All the samples collected (n= 400) in weeks 4 & 5 were processed. All samples were
processed for total aerobic plate count, Enterobacteriaceae count, Salmonella spp. and
Yersinia spp. isolation.
Table A3:1: Distribution of swabs collected at the abattoir and swabs processed for Yersinia isolation during the trial
Samples collected Samples processed for Yersinia isolation
After visual inspection
After traditional inspection
After visual inspection
After traditional inspection
Week 1 80 80 80 80 Week 2 100 100 50 49 Week 3 100 100 50 50 Week 4 100 100 100 100 Week 5 100 100 100 100 Total 480 480 380 379
Sampling methodology
1. Swabs were taken according to the FSA protocol described at UKmeat.org
[http://www.ukmeat.org/RedMeatCarcasses.htm]
2. Swabs were taken immediately after visual-only inspection and immediately after
traditional inspection in the abattoir line (see Figure A3:1); one member of the
project team took samples after the visual-only inspection and one after the
traditional inspection. These were the same two project personnel for the
duration of the trial, but positions were changed every day to avoid any bias due
to different sampling technique.
FS145003 Final report ANNEX 3 v6 Page 4 of 24
Figure A3:1: A pictorial representation of the microbiological swabbing points on the abattoir line.
3. Swabs were taken from different sides of the carcases to avoid sampling the
same area of the same animal after visual-only inspection and after traditional
inspection. Swabs after visual-only inspection point were always taken on the left
side of the carcass. Swabs after traditional inspection point were always taken on
the right side of the carcass. The sides used at each collection point were not
changed during the trial for two reasons: firstly, it was logistically challenging to
attempt to swab on the right side after the visual-only inspection in the study
abattoir. Secondly, the potential bias due to a particular side being more
contaminated due to handling of carcases was assessed by the authors and the
conclusion was that nearly half of the plant staff and MHIs were observed to be
left-handed (therefore the handling of carcases were expected to be balanced
between both sides in the overall number of carcases, as staff and MHIs change
positions routinely), so no bias was expected to influence the estimates.
4. Each swab was immediately identified (labelled) with date, sampling point
(visual-only or traditional) and a unique reference number in order to identify at
what point of the inspection time the sample has been taken at (beginning,
middle or end of the line) This formed the basis for the categories of the ‘line
position’ variable.
5. Approximately 200 samples were collected per week (100 after visual-only
inspection and 100 after traditional inspection), if logistically possible.
6. Daily sampling was spread through the line to enable to collect samples at the
beginning, middle and end of the line.
7. Carcases were selected for swabbing with a systematic random sampling
strategy. In order to reach the number of samples required for each day and
ensure that samples were evenly spread through the line, carcases were
selected with a routine depending on the number of pigs slaughtered that day,
FS145003 Final report ANNEX 3 v6 Page 5 of 24
the number of samples required for that day and the line speed (e.g. if 400 pigs
are slaughtered, 20 samples (at each point) required, and 200 carcases per hour
line speed: 1 carcase every 6 minutes or 1 carcase every 20 were swabbed to
reach the numbers for the day).
8. Once all samples are collected and properly identified for the day, they were
placed in the box with frozen freezing blocks and sent to the ERU laboratory in
Inverness to arrive within 24 hours.
Recording of data
The expected number of batches of outdoor pigs and total number of pigs to be
slaughtered every day was requested from the Official Veterinarian or the plant manager
every morning before starting. The sampling strategy was determined, as above, to
obtain the required daily number of swabs. Recalculation of the sampling strategy was
done if any logistical issue occurred that jeopardised the completion of all samples
before 11am (deadline for transport of samples to the laboratory) once the slaughter
started, for example, a delay in the slaughtering or arrival of pigs. Any lot expected to be
slaughtered after 10am was excluded from the calculation.
Date of sampling, number of sample (VTP001-VTP160 for the pilot week and 1-800 for
the rest of the weeks) and point of collection (visual-only or traditional) were recorded
every day on datasheets. Number of lots and carcases included in the sampling strategy
was recorded in a datasheet.
Sample processing
Samples were processed in the ERU laboratory 24 hours after collection in the abattoir.
Counts and isolation were carried out by two of the project team (see Tables A3:2a & b).
Total aerobic plate count, Enterobacteriaceae count, and Salmonella isolation were
carried out using the following methods:
1. Total aerobic plate count was carried out according to the BS EN ISO 4833:2003
(British Standard Institution, 2003a)
2. Enterobacteriaceae count was carried out according to the BS EN ISO 21528-
2:2004 (British Standard Institution, 2004)
3. Salmonella: Isolation of Salmonella was carried out using the BS EN ISO
6579:2002 (British Standard Institution, 2002 and Health Protection Agency,
2011b)
Yersinia isolation was carried out using the following methods:
1. British Standards Institution (2003b) BS EN ISO 10273:2003 Microbiology of food
and animal feeding stuffs - Horizontal methods for the detection of presumptive
pathogenic Yersinia enterocolitica. London: BSI
FS145003 Final report ANNEX 3 v6 Page 6 of 24
2. Health Protection Agency (2011c). Detection of Yersinia species. Microbiology
Services. Food, Water & Environmental Microbiology Standard Method F33:
Issue 1.0.
Detail of laboratory technique
10mls of maximum recovery diluent (MRD, Oxoid Ltd, Thermo Fisher Scientific, UK) was
added to each swab bag and processed in a stomacher for 60 seconds. 10ml of liquid
was retrieved from each bag and placed in a sterile, labelled universal container (neat
sample). This became the neat sample used to inoculate enrichment broths for
Salmonella and Yersinia culture and for enumeration of bacteria. 1ml of the neat sample
was added to 9ml MRD (Oxoid Ltd) and mixed with vortex for 5 seconds. This process
was repeated for preparing the decimal dilutions needed for both enumeration
techniques.
Total aerobic plate count
17ml standard plate count agar (APHA, Oxoid Ltd) was added to 1ml of each dilution in
a sterile Petri dish, incubated at 30°C ±1°C for 72 (±3) hours. Those plates with 15-300
colonies present were counted and these results used to calculate the total count
present on the original swab, as follows:
Number of bacteria = Σc/ (n1 + 0.1n2) d where
Σc = the sum of colonies counted
n1 = the number of dishes retained in the first dilution
n2 = the number of dishes retained in the second dilution
d = the dilution factor corresponding to the first dilution
The result obtained was corrected to two significant figures and multiplied by ten to
reflect the volume of diluent added to the swab.
Enterobacteriaceae counts
17ml violet red bile glucose agar (VRBGA, BO0197, Oxoid Ltd) was added to 1ml of
each dilution in a sterile Petri dish, the surface was overlaid with a further 10mls of
VRBGA. The completely set plates were incubated at 37°C (±1°C) for 24 (±2) hours.
Plates with <150 colonies were retained for counting. Confirmation of the identity as
Enterobacteriaceae was carried out on up to five colonies by performing an oxidase test
and a glucose fermentation test (Oxoid Ltd).
Count per ml of neat sample= (No of colonies confirmed/ No of colonies tested)
(Presumptive count/ Volume tested x dilution)
The result obtained was corrected to two significant figures and multiplied by ten to
reflect the volume of diluent added to the swab.
FS145003 Final report ANNEX 3 v6 Page 7 of 24
Salmonella culture
1ml of the neat sample was added to 10ml buffered peptone water (BPW, Oxoid Ltd)
and incubated at 37°C (±1°C) for 18 (±2) hours. After pre-enrichment selective
enrichment broths were inoculated, 1ml BPW was transferred to 10ml Muller Kauffmann
tetrathionate-novobiocin (MKTTn, Oxoid Ltd ) broth and incubated at 37°C (±1°C) for 24
(±1) hours and 0.1ml BPW was transferred to 10mls Rappaport Vassiliadis Broth with
soya (RVS, Oxoid Ltd) and incubated at 41.5°C (±1°C) for 24 (±1) hours.
Following incubation, the selective enrichment broths were subcultured to both brilliant
green agar (BGA, Oxoid Ltd) and xylose lysine deoxycholate agar (XLD, Oxoid Ltd)
plates using a 10µl loop, streaking for single colonies. Following incubation at 37°C
(±1°C) for 24 (±3) hours, the plates were examined for typical colonies.
Up to five suspect colonies representative of each broth and agar combination were,
when present, subcultured to blood (BA, Oxoid Ltd) and MacConkey (Mac8, Oxoid Ltd)
agars to produce pure growth of well isolated colonies, following incubation at 37°C
(±1°C) for 24 (±3) hours representative colonies from each subculture were tested for
autoagglutination and also agglutination with polyvalent O and H antigens (Oxoid Ltd).
Biochemical confirmation was carried out on colonies that produced any sign of
agglutination (n=1) or were phenotypically similar to Salmonella but failed to agglutinate.
Triple sugar iron agar slants (TSI, Lab M, Bury, UK) were inoculated along with a urease
broth (BioConnections, Wetherby, UK). Both were incubated at 37°C (±1°C) for 21 (±3)
hours. Confirmation of identity was continued using API 20E (bioMerieux UK Ltd)
screening kit, following the manufacturer’s instructions and BA and Mac purity plates
were set up.
During the sampling at the abattoir, we swabbed approximately 1 metre (100cm) of the
pig carcase with the length of the swab sponge (10cm). That gives us a total surface
swabbed of 10cm x 100cm= 1,000 cm2
(http://www.ukmeat.org/RedMeatCarcasses.htm). We divided the total counts for aerobic
plate and Enterobacteriaceae by 1,000 cm2 to obtain the number of bacteria per cm2.
FS145003 Final report ANNEX 3 v6 Page 8 of 24
Table A3:2a: Summary of microbiological procedures in the laboratory for total aerobic plate count, Enterobacteriaceae count, and Salmonella isolation
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Reference
Salmonella
Set up enrichment
Selective
enrichment
Selective isolation
media
Slide agglutinations,
purity plates
Set up
identifications
Identification as
probable Salmonella
BS EN ISO 6579:2002
Total aerobic plate counts
Set up serial dilutions and
duplicate counts
Counts
BS EN ISO 4833:2003
Enterobacteriacea
e counts
Set up serial dilutions and
duplicate counts
Counts
Purity plates
Set up
confirmations
Identification as
Enterobacteriaceae
BS EN ISO
21528-2:2004
Table A3:2b: Summary of microbiological procedures in the laboratory for Yersinia isolation
Day 1 Day 14 Day 15 Day 16 Day 17
Yersinia Set up cold enrichment
Selective isolation media
Purity plates
Set up identifications, motility tests
Identification as probable Yersinia
Roberts and Greenwood (2003). Practical Microbiology (3rd
Edition). Blackwell Publishing. Oxoid
FS145003 Final report ANNEX 3 v6 Page 9 of 24
Yersinia culture
Table A3:3: Enrichment broth and incubation conditions for Yersinia culture
Volume
of
sample
Enrichment
broth
Temperature Time Alkali treatment
(0.5% KOH in
0.5% saline)
Agar
0.1ml 9.9ml ITC 25°C (±1°C) 48 hours
(±2 hr)
No SSDC, CIN
1ml 9ml PSB 25°C (±1°C) 5 days static
incubation
Yes CIN
1ml 9ml TBW 9°C (±2°C) 14 days Yes CIN
The neat sample was added to enrichment broths and incubated as shown in Table A3:3.
After incubation, 10µl of the irgasan ticarcillin potassium chlorate broth (ITC broth base;
ticarcillin; potassium chlorate; Sigma-Aldrich Co Ltd) were subcultured onto both Cefsulodin
irgasan novobiocin agar (CIN, Oxoid Ltd) and Salmonella/Shigella agar with sodium
deoxycholate and calcium chloride agar (SSDC AGTC Bioproducts Ltd), both agars were
incubated 30°C (±1°C) for 21 (±3) hours, examined for typical colonies and reincubated at
the same temperature for a further 24 hours before re-examination.
10µl of the incubated peptone sorbitol broth (PSB, Sigma-Aldrich) broth was subcultured
directly onto CIN agar, and a further 0.5ml was mixed with 4.5ml potassium hydroxide
solution (KOH) and 10µl was immediately subcultured to CIN agar. The agar was incubated
30°C (±1°C) for 21 (±3) hours, examined for typical colonies and reincubated at 30°C for a
further 24 hours before re-examination.
The incubated Tris buffered peptone water (TBW, Oxoid Ltd, TRIS, Sigma-Aldrich) were also
alkali treated. One ml TBW was mixed with nine 9ml KOH, and immediately 10µl was
subcultured to CIN agar. The agar was incubated 30°C (±1°C) for 21 (±3) hours, examined
for typical colonies and reincubated at 30°C for a further 24 hours before re-examination.
Up to five suspect colonies from each agar/alkali treatment combination were subcultured to
blood (BA) and MacConkey (Mac) agars to produce pure growth of well isolated colonies.
Tests to determine the production of oxidase, urease and indole were set up along with a
Kligler’s agar slant. On Kligler’s agar Yersinia produce an acid butt with no gas or hydrogen
sulphide production and an unchanged slant. Some lactose positive strains have been
reported, none were identified in this study. Yersinia produce urease, may or may not
produce indole and do not produce oxidase.
Confirmation of identity was continued using API 20E screening kit, following the
manufacturer’s instructions and BA and Mac purity plates were set up.
It is noted that Yersinia plasmids may be spontaneously lost on culture above 30°C and
during prolonged passage. In this study, no culture occurred above 30°C and Yersinia was
stored at -80°C as soon as they were identified as such by API20E.
FS145003 Final report ANNEX 3 v6 Page 10 of 24
All swabs collected at the study abattoir during the trial the weeks 1, 4 and 5 were used to
isolate Yersinia. For the weeks 2 and 3, the isolation of Yersinia was restricted to one every
two samples with a systematic random sampling approach. A total of 759 samples were
processed at the end of the study for the purpose of isolation of Yersinia.
Data management
Results from the laboratory were recorded in a spreadsheet. Variables included in the
dataset were: abattoir, date of collection, individual id number (swab reference), inspection
method (collection point: after visual-only inspection or after traditional inspection), total
aerobic plate count, Enterobacteriaceae, Salmonella, day (4 to 23), line position and week.
The ‘Day’ variable is assigned from 1 to 23 for all days we collected swabs during the trial,
including the pilot week where swabs were collected (three days collection that week) for
Yersinia isolation only (not included in this report). This was an approximation to batch as
the batch was not recorded for each swab.
’Week’ was used as an approximation of season (i.e. the week where we collect swabs
during the trial.) Data from week 2 to 5 are included in this report as week 1 was used for
Yersinia isolation only.
‘Line position’: daily swabs were grouped in four groups, according to their position along the
slaughter line (from 1= swabs collected from carcases at the beginning of the line to 4=
swabs collected from carcases at the end of the line). We could expect the contamination to
increase in the carcases during the day, so carcases at the end of the day might be more
contaminated than carcases at the beginning of the day.
Outcome variables assessed in this study were total aerobic plate count, Enterobacteriaceae
plate count, Salmonella spp. isolation and Yersinia spp. isolation.
The variables were analysed to see if there was any difference between the two inspection
methods in terms of microbiological counts.
Statistical analysis
All analyses were performed with R version 2.12.1 from R Foundation for Statistical
Computing. http://www.r_project.org
The data used for this study were individual observations, sampled by systematic random
strategy from the same study population: carcases from fattening pigs from non-controlled
housing conditions. Samples were not intentionally taken from the same carcase after both
inspection methods (visual-only and traditional) and measures were in place to avoid
sampling the same area of the carcase if the same carcase was sampled at both inspection
points by chance. Only one study abattoir was used, so it was not possible to test if the
abattoir or the FSA team influences the results. The trial took place in five separate weeks
from the end of November 2011 to the middle of March 2012, which could be considered the
same season; nevertheless the effect of season was investigated at the level of week.
There was no recording of the batch (farm of origin of the pigs) from which the samples
were taken, Individual batches processed every day were recorded (with an average of two
batches used for sampling per day), so variable date is used as an approximation of farm of
FS145003 Final report ANNEX 3 v6 Page 11 of 24
origin, to study the possible effect of farm of origin on microbial contamination. Samples
were identified in four groups every day (from 1= at the beginning of the line to 4= at the end
of the line) to identify the location of carcases on time during the day. This was taken into
account in the analysis to study the effect of the position on the line on the results. Potential
bias of personnel collecting the samples was addressed during the sampling by rotating the
swab collection position daily. Potential bias of MHIs handling the carcases (different
methodologies of handling and inspection could increase or decrease the risk of
contaminating the carcase after traditional inspection) was considered and addressed as
MHIs were rotated every 20 minutes and different MHIs handled the carcases swabbed for
the purpose of this study.
Total aerobic plate count and Enterobacteriaceae count
Distributions of the counts were plotted in a histogram to see if they followed a normal
distribution. This was done separately for the two methods of inspection. Total aerobic plate
count and Enterobacteriaceae count variables were transformed into log10 total aerobic plate
count and log10 Enterobacteriaceae count to try to fulfil the normality assumption. The mean
of the microbial counts with their 95% confidence interval (C.I.) were calculated for both
inspection methods. For total aerobic plate count the estimates calculated were the mean of
the logs. For the Enterobacteriaceae count the estimates were the mean of the values, as
the log scale has a large number of zeros.
The student t-test for comparison of the mean for aerobic plate count was applied to analyse
the differences between the mean of the count after visual-only inspection and the mean of
the count after traditional inspection. For the Enterobacteriaceae count there were a large
number of zeros, so the variable was categorised as a binary variable: presence/absence.
For the categorised variables (presence/absence) a chi-squared test was used to see if
there was an association between these variables and the inspection method. The samples
with more than zero Enterobacteriaceae plate count were transformed to log10 and a student
t-test was used to compare the means between the inspection methods.
Linear models were also applied to investigate the association between the inspection
method and the microbial contamination of carcases. Other variables included in the models
were inspection method, week, date and line position, in order to study the effects of season,
farm of origin, and position of carcase in the line. The variables were selected to enter in
the multivariable model if P<0.15.
Yersinia spp. isolation
The outcome variable was categorized as a binary variable: presence/absence. For the
univariable analyses a logistic regression model (Wald test) was used to test if there was an
association between each of the variables individually and the presence of Yersinia. The
variables tested in the univariable analyses were: inspection method, week, date, and line
position. The aim is to study the effects of inspection method, season, farm of origin, and
position of carcase in the line.
Any variables with a p<0.15 in the univariable analysis were selected to be used in the
multivariable analysis. A logistic regression model (Wald test) was also used for this, to test
if there was an association between the selected variables and the presence of Yersinia.
FS145003 Final report ANNEX 3 v6 Page 12 of 24
All
Due to the number of analyses performed in the comparison (n=4) we adjusted the
significance level, using Bonferroni correction (n =4).
For the purpose of this study, therefore, we will consider statistical significant any estimate
with a p<0.0127 for all tests performed.
RESULTS
Total aerobic plate count, Enterobacteriaceae count and Salmonella spp.
isolation
Farms, batches, and carcases available for sampling
A total of 800 samples were collected during the trial for the purpose of this study. 400
samples were collected after visual-only inspection and 400 samples after traditional
inspection (see Table A3:4). A total of 44 batches from ten farms and 7,931 carcases were
included in the sampling frame. The number of carcases, batches and farms are lower than
the number used for conditions during the same four weeks, due to logistic requirements.
Samples had to be dispatched before 11:00 am every day (in order to arrive to laboratory
within 24 hours), so pigs from batches included in the condition study, but not expected to be
slaughtered before 10:00 am were not included in the selection for sampling. This is not
expected to significantly affect the results.
The number of total swabs collected for the purpose of the study was slightly lower than the
proposed sample size for total aerobic plate count and Enterobacteriaceae. This should not
affect the results, as the prevalence actually found in the carcases during the trial was lower
than the worst scenario assumption, therefore a lower number of swabs will suffice to reach
the same power and significance level (80% and 95% respectively).
TableA3:4: Summary statistics for the number of swabs collected per day over the subset of the study period applicable to total aerobic plate count and Enterobacteriaceae counts and Salmonella spp. isolation.
Number of swabs collected per day
Min Mode Median Mean Max
Visual-only
inspection
20 20 20 20 20
Traditional
inspection
9 20 20 20 24
Total 29 40 40 40 44
Descriptive analysis of microbial contamination in carcases after both inspection
methods
A description of the mean of all outcomes analysed in the study is presented in Tables 3 and
4. For the total count plate count the estimates are presented as the log10 of the actual
results. For the Enterobacteriaceae count the large number of zeros made it impossible to
present the estimates as their log values; the actual estimates are presented instead.
FS145003 Final report ANNEX 3 v6 Page 13 of 24
Table A3:5: Descriptive analysis of total aerobic plate count on carcases during the trial after both inspection methods.
Mean of the log10
of total aerobic plate count
Mean Standard deviation
95% C.I.
After traditional inspection 1.497 1.03 1.396 – 1.598 After visual-inspection inspection 1.421 0.95 1.327 – 1.514
Table A3:6: Descriptive analysis of Enterobacteriaceae count on carcases during the trial after both inspection methods.
Mean of Enterobacteriaceae count
Mean Standard deviation
95% C.I.
After traditional inspection 0.359 3.19 0.046 – 0.673 After visual-inspection inspection 0.060 0.64 -0.003 – 0.124
Salmonella counts were zero for all the samples. No Salmonella spp. was isolated from any
of the swabs collected for the purpose of the study. No analysis has, therefore, been carried
to identify the difference between the risks of cross contamination with Salmonella in
carcases from fattening pigs from non-controlled housing conditions in the study abattoir.
Distribution of the microbial counts in carcases after both inspection methods
Distribution of the count of each microbial contamination of carcases, total aerobic plate
count and Enterobacteriaceae count, were plotted to see if they follow the normal
distribution.
The plots (Figure A3:2 and A3:4) of the variable total aerobic plate count and
Enterobacteriaceae count suggested that a log transformation should be applied to both of
the data sets (see Figures A3:3 and A3:5).
FS145003 Final report ANNEX 3 v6 Page 14 of 24
Figure A3:2: Histogram of the total aerobic plate count
Figure A3:3: Histogram of the log transformation of the aerobic plate count
FS145003 Final report ANNEX 3 v6 Page 15 of 24
Figure A3:4: Histogram of Enterobacteriaceae count
Figure A3:5: Histogram of the log of Enterobacteriaceae count
FS145003 Final report ANNEX 3 v6 Page 16 of 24
Microbial contamination of carcases (total aerobic plate count and Enterobacteriaceae
count) was plotted separately by inspection methods to see if there was any suggestion of a
difference between them. No difference was apparent in the total aerobic plate counts
(Figure A3:6).
Figure A3:6: Distribution of log of total aerobic plate count for each inspection method
Due to the large number of zeros (565 samples) in the Enterobacteriaceae count, we
categorised this variable into presence/absence and plotted the counts just for the group
where it was present (i.e. Enterobacteriaceae count > 0). A slight difference is apparent in
the Enterobacteriaceae count between both inspection methods; the microbial contamination
with Enterobacteriaceae being lower after visual-only contamination (Figure A3:7).
FS145003 Final report ANNEX 3 v6 Page 17 of 24
Figure A3:7: Distribution of log of Enterobacteriaceae count for each inspection method
Univariable analyses
There is no statistical difference in the total aerobic plate counts between the inspection
methods, using the student t-test to compare the two means (Table A3:7).
Table A3:7: Results of student t-test for the log of total aerobic plate count
Inspection method Mean Difference between the
mean (95%C.I.)
P value
Traditional 1.497 0.08 (-0.06, 0.21) 0.2772
Visual 1.421
The variable Enterobacteriaceae count (Figure A3:4) had a high number of samples with
zero counts. After categorisation of this variable as absence/presence of Enterobacteriaceae
(Table A3:8) and using a chi-squared test to test if there was an association between the
inspection method and the Enterobacteriaceae detection, there was no association between
the categorized Enterobacteriaceae variable and the inspection method (p=0.76).
Table A3:8: Enterobacteriaceae presence/absence by inspection method
Inspection method
Traditional Visual
Enterobacteriaceae
count
Absence 280 285
Presence 120 115
When the subset of counts for Enterobacteriaceae contamination when present (i.e. >0,
n=235) were compared, there is a statistical significance difference in the
FS145003 Final report ANNEX 3 v6 Page 18 of 24
Enterobacteriaceae contamination of carcases between inspection methods.
Enterobacteriaceae contamination is lower after visual-only inspection compared to
Enterobacteriaceae contamination after traditional inspection (Table A3:9).
Table A3:9: Student t-test for the comparison between the two inspection methods for Enterobacteriaceae counts where Enterobacteriaceae = presence.
Inspection method Mean Difference between the
mean (95%C.I.)
P value
Traditional -1.14 0.43 (0.22, 0.63) <0.001
Visual -1.57
Multivariable analyses
The results from the use of a linear model to test if the other variables (week, date and line
position) influence the total aerobic plate count indicate that the variable date influences the
outcome (results not shown). This seems to imply that the batch/farm or origin is the only
variable that influences the results in terms of aerobic plate count.
We also used linear models to test the category ‘presence of Enterobacteriaceae (n=235
samples)’, with the Enterobacteriaceae count as outcome and the inspection methods,
weeks, date and the line position as fixed factors. The only statistical significant variable was
the inspection method, implying that the inspection method is the only variable that
influences the results in terms of Enterobacteriaceae count. For this type of variable (more
than half of the samples had zero counts) a zero-inflated binomial model fits the data better.
Yersinia spp. isolation
Farms, batches, and carcases available for sampling
A total of 960 samples (see Table A3:10) were collected during the trial for the purpose of
this study: 160 in the trial week (week 1) and 800 in weeks 2 to 5, of which 480 samples
were collected after visual-only inspection and 480 samples after traditional inspection (see
Table 1). These swabs came from a sampling frame of 54 batches from 12 farms consisting
of 9,633 carcases. Only approximately half of the collected swabs were processed for the
isolation of Yersinia during the weeks 2 and 3. This brings the total number of swabs
processed down to 759 (380 after visual-only inspection and 379 after traditional inspection).
The number of total swabs collected for the purpose of the study was larger than the
proposed sample size for Yersinia (320: 160 after traditional inspection and 160 after visual-
only inspection). This should be more than sufficient to reach the same power and
significance level (80% and 95% respectively).
FS145003 Final report ANNEX 3 v6 Page 19 of 24
Table A3:10: Summary statistics for the number of swabs collected per day over the full study period.
Number of swabs collected per day
Min Mode Median Mean Max
Visual-only
inspection
13 20 20 21 40
Traditional
inspection
9 20 20 21 40
Total 22 40 40 42 80
Descriptive analysis of microbial contamination with Yersinia in carcases after both
inspection methods
Table A3:11: Distribution of Yersinia isolated from carcases swabs after both inspection methods during the trial.
Yersinia
enterocolitica
n (percentage*)
Yersinia
pseudotuberculosis
n (percentage*)
Yersinia
fredericksenii
n (percentage*)
Traditional Visual-only Traditional Visual-only Traditional Visual-
only
Week 1 5 (6.25%) 2 (2.5%) 1 (1.25%) 1 (1.25%)
Week 2
Week 3 1 (2%)
Week 4 1 (1%)
Week 5 1 (1%)
Total 6 (1.6%**) 4 (1.1%**) 1 (0.3%**) 1 (0.3%**)
*% of samples collected that week
** % of the total samples collected during the trial
During the pilot study (first week in November 2011) 160 carcase swabs were tested for
Yersinia; seven Yersinia enterocolitica, one Yersinia pseudotuberculosis, and one Yersinia
fredericksenii were isolated from the carcase swabs received in that week.
For the rest of the trial (four weeks between 16th January 2012 and 16th March 2012) 599
carcase swabs were tested for Yersinia; a total of three Yersinia enterocolitica were isolated
from those carcase swabs.
The distribution of Yersinia isolated from the samples after both inspections during the trial is
shown in Table A3:11. During the first week of the trial, nine Yersinia were isolated from the
FS145003 Final report ANNEX 3 v6 Page 20 of 24
carcase swabs: seven Yersinia enterocolitica, five (6.25% of samples collected that week)
after traditional inspection and two (2.5% of samples collected that week) after visual-only
inspection; one Yersinia pseudotuberculosis (1.25% of samples collected on that week) after
visual-only inspection; and one Yersinia fredericksenii (1.25% of samples collected on that
week) after traditional inspection. No Yersinia of any type was isolated in the second week of
the trial. During the third week, one Yersinia enterolitica (2% of samples collected on that
week) was isolated after traditional inspection. During the fourth week, one Yersinia
enterolitica (1% of samples collected on that week) was isolated after visual-only inspection.
During the fifth week, one Yersinia enterolitica (1% of samples collected on that week) was
isolated after visual-only inspection.
In total, twelve (1.6% of the total samples collected during the trial) Yersinia were
isolated from the swabs: seven (0.9% of the total samples collected after during the trial)
after traditional inspection, six of them Yersinia enterolitica and one Yersinia
fredericksenii; five (0.6% of the total samples collected after during the trial) after visual-
only inspection, four of them Yersinia enterocolitica and one Yersinia
pseudotuberculosis.
Univariable analyses
For Yersinia detection, the outcome variable was categorized as presence or absence,
regardless of the type of Yersinia. From now on, we consider a sample being positive for
Yersinia any sample positive for Yersinia enterolitica, Yersinia pseudotuberculosis or
Yersinia fredericksenii.
Table A3:12: Detection of Yersina for the inspection methods
Inspection method
Traditional Visual
Yersinia isolation Absence 372 375
Presence 7 5
The majority of the samples were negative (Table A3:12).
There is no statistical difference (p=0.55) in the Yersinia detection in carcases between the
inspection methods (Table A3:12).
Carcases sampled at the end of the line had more risk of having Yersinia than at the
beginning of the line (p=0.09).
Carcases sampled in week 1 had more risk of presence of Yersinia than in other weeks
(p<0.01).
Carcases sampled at two dates (28th and 29th November 2011) had more risk of presence of
Yersinia than in the rest of the dates (p<0.03).
FS145003 Final report ANNEX 3 v6 Page 21 of 24
Multivariable analyses
The variables at the univariable analyses selected to enter the multivariable model were
week, line position and date.
In the final multivariable model there was a statistically significant association with the
presence of Yersinia for the variable date, specifically the 29th of November 2011 (p<0.001).
Two batches (i.e. two different farms) were processed on that day; one of the farm provided
pigs for the rest of the trial and the other one only sent animals on that day. Otherwise, there
was no statistical difference (p=0.55) in the Yersinia detection in carcases between the
inspection methods.
FS145003 Final report ANNEX 3 v6 Page 22 of 24
DISCUSSION
The EU Regulation No 1441/2007 (Anonymous, 2007) imposes microbiological criteria for
foodstuffs. Chapter 2 of this Regulation defines the hygiene status of the process by the
level of microbial contamination. If we apply these microbiological criteria to the results of the
samples in the study, then as both the mean of the Enterobacteriaceae count and the mean
of the total aerobic plate count were below the lower limit it was considered to be
‘satisfactory’ (Table A3:13). This abattoir is considered a satisfactory abattoir as far as
hygiene is concerned when measured by microbiological checks of carcases after
inspection.
Table A3:13: Swabbing criteria for pig carcasses [http://www.ukmeat.org/RedMeatCarcasses.htm]
Total aerobic plate Count
Enterobacteriaceae count
Salmonella
Unacceptable mean log /number of positives is equal to or above
4.3 2.3 5/50
Acceptable mean log is below 4.3 2.3
Satisfactory mean log / number of positives is below
3.3 1.3 5/50
The same level of total aerobic plate (TAP) counts was observed with each inspection
method; however, lower levels of Enterobacteriaceae counts were observed after visual-only
inspection. The trial was carried out in only one abattoir. The study abattoir was particularly
clean, with a very good protocol of hygienic measures implemented by both the plant
personnel and the FSA personnel. Plant personnel and FSA personnel had a very good
routine of washing and disinfecting hands and knives on the line. This was the norm and was
not just due to the occurrence of the trial. This emphasis on good hygiene practice would
result in a lower level of any cross contamination of any carcases. The microbiological
outcomes of the study (TAP and Enterobacteriaceae counts) were not a surprise for the
authors, when they compare the study abattoir to other abattoirs that they have visited in the
past in the UK. If, as the results of the study demonstrate, a reduction of contamination with
Enterobacteriaceae can be achieved by the use of visual-only inspection in an abattoir with a
very low prevalence of contamination in their carcases, it would also be expected to be
observed in abattoirs with a higher initial prevalence of contamination i.e. visual-only
inspection results in a lower level of any cross contamination of carcases.
By using only one study abattoir, we have reduced the study to only one FSA team. As
explained above, the hygiene routine of this team is very good. A complete ‘hands-off’
visual-only system was followed by all MIHs carrying out the trial; this should identify the
largest apparent gain that can be made between the two inspection systems.
No Salmonella spp. was isolated from any of the 800 swabs processed during the trial.
According to the assumption made prior to the start of the trial, based on the prevalence of
Salmonella observed in carcases in UK, (up to 9.64% or 13.5% (depending on the reference
- Unpublished data BPEX/FSA WP4 and Anonymous, 2008, respectively) we expected to
isolate some Salmonella spp. The FSA defines the level of Salmonella in an abattoir as
unacceptable [[http://www.ukmeat.org/RedMeatCarcasses.htm] when Salmonella spp. is
detected in more than five out of 50 samples (10%). We collected 800 samples, so even if
FS145003 Final report ANNEX 3 v6 Page 23 of 24
we isolated Salmonella in up to 16 of the samples, the abattoir would have remained within
the acceptable range. Swabs were taken in the side of the carcase, as we tried to identify
any cross contamination. The study abattoir follows a particularly good hygiene practice and
that could contribute to the why we did not isolate any Salmonella. It would also be useful to
know more about the disease/infection status of the production units involved in the study
and how they compare to both the general non-controlled housing fattening pig production
unit population and the controlled housing fattening pig production unit population, with
respect to Salmonella disease/infection status i.e. are these particularly clean pigs coming
into an abattoir with good hygiene/cross-contamination control? Such data are currently not
available to us.
We would not expect to have experienced any difference in the results had we included all
outdoors batches received and processed at the abattoir. Only five batches arrived at the
abattoir after 10 am and were, therefore, excluded from the sampling frame. They were not
constantly from the same producers, so no bias is expected.
The trial has been carried out in only one study abattoir, in the East of England. For logistical
reasons a second abattoir in the south west of the UK was not included in the trial. The
prevalence of microbiological agents, such as Salmonella and Yersinia in pigs might be
different (Anonymous, 2008), depending on the locations of the farms of origin. This
hypothesis gains some support from the statistically significant difference in Yersinia
contamination presence that was observed, after adjusting for an approximation of farms of
origin (date variable) for one particular date: the 29th of November 2011. On that particular
day two different farms were recorded as delivering animals to the abattoir. One of the farms
sent animals on most of the days in the following weeks for the rest of the trial. The other
farm sent animals exclusively on that day. It is possible that this one farm was the source of
the Yersinia that was detected.
However, most of pig farms are located in the east of England and due to the large number
of outdoor pigs processed in the study abattoir we expect to have covered different areas of
‘outdoor’ pig production in the UK. To confirm this we would need (as mentioned in Annex 2)
either demographic and spatial location data to determine the geographical distribution of
‘outdoor’ pig production in the UK and to compare it with the production units included in the
trial, or (for a more crude approximation) an indication of what proportion of the total
processing of ‘outdoor’ pigs from non-controlled housing conditions is done at the study
abattoir. Such data are not readily available. The difference in Enterobacteriaceae
contamination between inspection methods was statistically significant after adjusting for an
approximation of farms of origin (date variable). Again, further research into the coverage of
the target population that was achieved would assist in the assessment of the validity of this
result and whether it can be extrapolated to the non-study population within the UK.
FS145003 Final report ANNEX 3 v6 Page 24 of 24
CONCLUSIONS
Carcases from pigs from non-controlled housing conditions in the study abattoir after visual-
only inspection have a similar level of contamination with Yersinia spp. than after traditional
inspection, i.e. the level of contamination after both inspections is the same. However, a
lower level of contamination with Enterobacteriaceae was found after visual inspection than
after traditional inspection. The total aerobic plate counts are similar, i.e. the level of
contamination after both inspections is the same; and no Salmonella spp. was isolated from
any carcases. These results suggest that we were able to reduce the microbial load i.e. the
contamination of carcases by changing the post-mortem inspection method to a visual
system where handling of carcases by FSA personnel was minimised.
Total aerobic plate count and Enterobacteriaceae count are commonly used as an
approximation of any microbiological contamination in carcases. So we can say that the risk
of any microbiological contamination in carcases is lower after visual-only post-mortem
inspection compared to traditional post-mortem inspection.
We can conclude that as this result has been observed in a particularly clean abattoir,
results are expected to be observed in any abattoir with level of contamination as low as and
higher than the study premises.
FS145003 Final report ANNEX 4 v6 Page 1 of 54
ANNEX 4
FINAL REPORT FOR PROJECT FS145003
REPORT OF THE RISK ASSESSMENT FOR OBJECTIVE 8
This purpose of this work was to undertake a formal, mostly qualitative, risk assessment,
based on guidelines described by the Codex Alimentarius Commission (CAC), on the impact
of the implementation of visual-only inspection for fattening pigs from non-controlled housing
conditions and the impacts that this could have in terms of public health, animal health,
animal welfare and the allocation of resources
We have used a modified CAC risk assessment approach to qualitatively assess the
potential change in risks to human (public health via a food-borne route), animal health and
animal welfare of a change in the meat inspection method, from the traditional method
currently employed to a visual-only (‗hands-off‘) methodology, for fattening pigs from non-
controlled housing management systems i.e. raised outdoors from weaning to slaughter. We
have not considered the component of public health risk that is due to occupational
exposure. We have used data from previous work, scientific literature, publically available
information and our own field study to inform the risk assessment. Based on this information
we have taken a cautious approach and considered a worse case scenario.
Of the five public health hazards we have assessed (endocarditis, granulomatous lesions,
Salmonella spp., Yersinia spp., and the hygiene process indicators - total aerobic plate count
and Enterobacteriaceae count) only two have a revised risk on a change in inspection
method. The risk for hazards associated with endocarditis lesions changes from negligible to
non-negligible, i.e. very low, while from the results of the Enterobacteriaceae count analysis
it is possible that the risk of cross-contamination between carcases is reduced. Only two
animal health hazards were identified and assessed (endocarditis and granulomatous
lesions). Again, endocarditis has a revised risk on a change in inspection method from
negligible to non-negligible i.e. very low. Despite the revised risk classification for public and
animal health, attributable to the reduced detection of endocarditis lesions by visual-only
inspection compared to traditional inspection for outdoor pigs, the fact still remains that
outdoor pigs from non-controlled housing conditions present at least the same, if not less
(Hill et al., 2011), of a risk than indoor pigs from controlled housing conditions. Visual
inspection is acceptable for pigs from indoor, controlled and integrated management
systems (Anon., 2004b); therefore there is no reason relevant to the public health risk
presented to exclude outdoor pigs purely on grounds of the management system from which
they originate. This is also the case for the animal health risk. Action by producers is unlikely
to be taken on the basis of information received about endocarditis lesions from post-mortem
data feedback. Action would be taken in response to clinical signs in live pigs with
associated production losses and their economic impact for the causal agents associated
with endocarditis lesions (Strepococcus spp, including S. suis & E. rhusiopathiae).
One of the arguments for a move from a traditional palpation and incision inspection system
to a visual-only based one is that it could reduce cross contamination of carcases that would
occur via the hands and knives of meat inspectors. In our field study, no difference was
found in the isolation of Yersinia spp. or Salmonella spp., total aerobic plate count or the
FS145003 Final report ANNEX 4 v6 Page 2 of 54
presence/absence of Enterobacteriaceae; however, when present the Enterobacteriaceae
count was lower on carcases that had been visually inspected than traditionally inspected,
implying less contamination. The abattoir used for the field study had a particularly good
hygiene process. It is possible that a change in the inspection method from traditional to
visual would lead to a similar result in any abattoir with a level of contamination as low as or
higher than the study premises. If the level of contamination is lower, then it could be
hypothesised that the potential for cross-contamination would be lower; however, we cannot
draw that directly as a conclusion from our study.
The primary benefit of a visual-only system of inspection that encompassed pigs from non-
controlled housing conditions would be, in the United Kingdom (UK), the ability to implement
such an inspection system for all pigs. At present although it is theoretically possible to do so
for pigs from controlled housing conditions, in terms of the regulatory process, such systems
have not been implemented because slaughterhouses process fattening pigs from different
management systems.
From this risk assessment, based on current evidence, we do not consider that there is any
appreciable additional risk to public health, animal health or animal welfare from visual-only
inspection of fattening pigs from non-controlled housing conditions in the UK over and above
that which currently exists with traditional inspection.
FS145003 Final report ANNEX 4 v6 Page 3 of 54
TABLE OF CONTENTS
Background ........................................................................................................................... 7
The problem ....................................................................................................................... 7
Project FS145003 ............................................................................................................... 7
Risk Analysis ........................................................................................................................ 7
Objective 8.......................................................................................................................... 8
Risk Assessment .................................................................................................................. 9
Previous work ..................................................................................................................... 9
Define the question ........................................................................................................... 11
‘How would the risk profile change if fattening pigs from non-controlled housing conditions
are visually inspected, in terms of: ........................................................................................ 11
What is the baseline against which any change in the risk profile is to be considered? ...... 11
Definitions ........................................................................................................................................... 11
1. What is the relative risk posed by visual-only inspection of ‘outdoor’ pigs over
traditional inspection of ‘outdoor’ pigs? ................................................................................. 12
2. What is the absolute risk of visual-only inspected outdoor pigs? ................................. 12
Risk pathway .................................................................................................................... 13
Hazard Identification ......................................................................................................... 15
Hazard identification for Question 1: ................................................................................. 15
Is the sensitivity of detecting a condition affected by the inspection method? ..................... 15
Previous work ..................................................................................................................................... 15
Hazard identification 1PAH: ................................................................................................................ 16
Hazard identification 1AW: ................................................................................................................. 17
Study FS145003 Objective 3 .............................................................................................................. 18
What conditions in free-range pigs were observed in our study at statistically different
frequencies by the two inspection methods? ........................................................................ 18
Do they pose a potential hazard to public health? ................................................................ 20
Do they pose a potential hazard to animal health? ............................................................... 20
Do they pose a potential hazard to animal welfare? ............................................................. 21
Hazard identification 1PAH & 1AH & 1AW: ........................................................................................ 22
Do our study findings support the animal health associated public health hazards identified
in previous work? .................................................................................................................. 22
Hazard identification 1PAH: ................................................................................................................ 22
Hazard identification for Question 2: ................................................................................. 22
Is the level of carcass contamination affected by the inspection method? ........................... 22
A – Identify the micro-organisms or the microbial toxins of concern with food (CAC, 1999) 22
Previous work ..................................................................................................................................... 22
Hazard identification 2A-PHCM: ......................................................................................................... 23
Study FS145003 Objectives 6 & 7...................................................................................................... 25
B – Identify other non-microbial carcass contaminants that might be affected by the
inspection method. ................................................................................................................ 25
FS145003 Final report ANNEX 4 v6 Page 4 of 54
Carcass meat (internal) contaminants ............................................................................... 25
Hazard identification 2B –PH CI: ........................................................................................................ 26
Carcass external contaminants ......................................................................................... 26
Study FS145003 Objective 3 .............................................................................................................. 26
Hazard identification 2B –PH CE:....................................................................................................... 27
Hazard Characterisation ................................................................................................... 27
Endocarditis in pigs ........................................................................................................... 27
Endocarditis - Streptococcus spp. including Streptococcus suis ....................................................... 27
Endocarditis - Erysipelothrix rhusiopathiae ........................................................................................ 28
Granulomatous lesions - Rhodococcus equi ...................................................................................... 28
Granulomatous lesions - Mycobacterium spp. ................................................................................... 29
Salmonella spp. .................................................................................................................................. 29
Yersinia spp. ....................................................................................................................................... 29
Total aerobic and Enterobacteriacae counts ...................................................................................... 30
Exposure Assessment ...................................................................................................... 30
What is the current baseline exposure assessment with the traditional inspection method? ......................................................................................................................................... 31
What is the contribution to the actual public health exposure of organisms associated with
endocarditis and granulomatous lesions in pork meat? ........................................................ 31
Endocarditis - Streptococcus spp. including Streptococcus suis ....................................................... 31
Endocarditis - Erysipelothrix rhusiopathiae ........................................................................................ 31
Granulomatous lesions - Rhodococcus equi ...................................................................................... 31
Granulomatous lesions - Mycobaterium spp.: .................................................................................... 31
Endocarditis and granulomatous lesions public health exposure assessment summary .................. 32
What is the contribution to the actual public health exposure of organisms associated with
carcass microbial contamination of pork meat? .................................................................... 32
Salmonella spp. .................................................................................................................................. 32
Y. enterocolitica* ................................................................................................................................. 33
Total aerobic and Enterobacteriacae counts ...................................................................................... 34
Microbiological public health exposure assessment summary .......................................................... 34
What is the baseline for animal health? i.e. disease prevention and control? .................... 34
What contribution does information derived from post-mortem inspection data have in the
prevention and control of disease in the outdoor pig population? ........................................ 34
Endocarditis – general ........................................................................................................................ 34
Endocarditis - Streptococcus spp. including Streptococcus suis ....................................................... 34
Endocarditis - Erysipelothrix rhusiopathiae ........................................................................................ 34
Granulomatous lesions - General ....................................................................................................... 34
Granulomatous lesions - Rhodoccus equi .......................................................................................... 35
Granulomatous lesions - Mycobaterium spp: ..................................................................................... 35
Salmonella spp. .................................................................................................................................. 35
Y. enterocolitica* ................................................................................................................................. 35
Risk Characterisation ........................................................................................................ 36
FS145003 Final report ANNEX 4 v6 Page 5 of 54
Is there a change in the risk profile if the inspection method is changed from traditional to visual-only? ....................................................................................................................... 36
How many pigs from non-controlled housing conditions are currently processed annually in
Great Britain? ........................................................................................................................ 37
Risk assessment discussion ............................................................................................. 42
Risk assessment conclusions ........................................................................................... 44
Risk mitigation measures .................................................................................................. 45
Impacts ............................................................................................................................. 46
What would be the impact of the introduction of visual-only inspection of fattening pigs from
non-controlled housing conditions in the UK on…? .............................................................. 46
Impact on public health ..................................................................................................... 46
Impact on occupational exposure ..................................................................................... 46
Impact on animal health .................................................................................................... 46
Impact on animal welfare .................................................................................................. 47
Impacts on resources ....................................................................................................... 47
Other impacts ................................................................................................................... 48
Benefits ............................................................................................................................ 49
References ......................................................................................................................... 52
FS145003 Final report ANNEX 4 v6 Page 6 of 54
TABLES AND FIGURES
Figure A4:1: The components of risk analysis ....................................................................... 8
Table A4:1: Comparison of the components of two risk assessment approaches ................. 8
Table A4:2: Differences in visual-only inspection compared to traditional inspection in outdoor pigs during FSA trial FS145003.............................................................................. 14
Table A4:3: Conditions for which detection might be affected by the inspection method and their relevance to a potential change in risk adapted from Hill et al., (2011) ........................ 15
Table A4:4: Conditions for which detection might be affected by the inspection method and their relevance to a potential change in risk to humans adapted from the Danish Way (Alban et al., 2008). ........................................................................................................................ 16
Table A4:5: Descriptive analysis of the frequency of the eight conditions (with a statistically significant difference between the two inspection methods) found in pigs from non-controlled housing conditions at post-mortem meat inspection by the two inspection methods; number (n), percent of total carcases inspected (%) and 95% confidence interval (95% C.I.) .......... 19
Table A4:6: Summary of the eight conditions where there was a statistical significant difference between visual-only and traditional inspection methods...................................... 19
Table A4:7: Hazard identification – conditions that detection of which could be or were affected by the inspection method and their relevance to a potential change in risk ............ 24
Table A4:8: The descriptive analyses of the frequencies (number=n [%] and where appropriate 95% confidence interval, C.I.) found in the study abattoir in FS145003 by the two inspection methods for the hazards identified...................................................................... 37
Table A4:9: Student t-test for the comparison between the two inspection methods for Enterobacteriaceae counts where Enterobacteriaceae = presence and for the log10 of total aerobic plate counts. ........................................................................................................... 37
Table A4:10: The predicted guesstimates of the total annual numbers of hearts/carcases potentially missed if visual-only inspection was implemented as per the trial conditions and prevalence in all ‗outdoor finished‘ pigs was the same as per the trial conditions. ............... 38
Table A4:11: Summary of the Risk Characterisation for Public Health for the five hazards for which detection could be or was affected by the inspection method .................................... 40
Table A4:12: Summary of the Risk Characterisation for Animal Health (AH) for the two major hazards for which detection could be or was affected by the inspection method ................. 41
Table A4:13: Potential impacts on resources of the introduction of visual-only inspection for fattening pigs ...................................................................................................................... 47
Figure A4:2 Public and animal health hazards that arise from animal health conditions and their relative risks comparing inspection methods ............................................................... 50
Figure A4:3: Public health (foodborne) hazards from carcass microbial contaminants and their relative risks comparing inspection methods ............................................................... 51
FS145003 Final report ANNEX 4 v6 Page 7 of 54
BACKGROUND
The problem
The focus of traditional methods of meat inspection is on the detection of gross lesions or
flaws in the carcass. Such methods of meat inspection are not always suitable for detecting
some important food-borne pathogens. Modernisation of post-mortem inspection regulations
in the European Union (EU) means that, provided that certain requirements are met,
carcases of fattening pigs reared under controlled housing conditions in integrated
production systems since weaning need only undergo visual inspection (EC Regulation
854/2004). This does not involve palpation or incisions and may reduce the risk of cross
carcass contamination. Uptake by the UK pig industry has been low because
slaughterhouses accept a mixture of indoor and outdoor reared pigs throughout the day and
the latter still have to be inspected by traditional means.
Project FS145003
Our project – ‗Trial of visual inspection of fattening pigs from non-controlled housing
conditions‘ - included a field trial of visual versus traditional meat inspection of fattening pigs
from non-controlled housing conditions. Batches of such pigs (termed ‗outdoor‘ or ‗free-
range)‘ were inspected by both visual and traditional methods and carcass sponge samples
were taken from a subset of pigs on the slaughter line after each of the inspection points.
The conditions found by each inspection method were recorded and compared (Objectives
1, 2 & 3). The microbiological work included total aerobic plate counts; Enterobacteriaceae
counts, and the isolation of Salmonella and Yersinia (Objectives 6 & 7). Obstacles to the
implementation of a risk-based visual-only inspection system were also investigated
(Objective 5). In addition, historic data from a full calendar year of traditional meat inspection
in the abattoir was analysed, in order to establish a baseline for the frequency of conditions
recorded by this method for pigs from different management systems (Objective 4).
The results from these investigations have been used to inform a risk assessment. Objective
8 is to undertake a formal, mostly qualitative, risk assessment, based on guidelines
described by the Codex Alimentarius Commission (CAC), on the impact of the
implementation of visual-only inspection for fattening pigs from non-controlled housing
conditions and the impacts that this could have in terms of public health, animal health,
animal welfare and the allocation of resources. This work is reported here.
RISK ANALYSIS
Risk analysis consists of four components – hazard identification, risk assessment, risk
management and risk communication. The purpose of this work is predominantly risk
assessment i.e. to address the first two parts: hazard identification and risk assessment
(Figure A4:1). Communication is required throughout the process; however whether the risk
is acceptable is, ultimately, a risk management decision. Risk management includes the
consideration of: the identified and assessed risks versus the potential benefits and the
costs; possible options, risk mitigation and reduction measures; implementation and
subsequent monitoring needs.
FS145003 Final report ANNEX 4 v6 Page 8 of 54
Figure A4:1: The components of risk analysis
There are two recognised, formalised approaches to risk assessment. These are the World
Organisation for Animal Health (OIE, 2004) Terrestrial Animal Health Code and that of the
Codex Alimentarius Commission (CAC, 1999). The stages and terminology used in these
systems, and their relationships are described below (Table A4:1).
Table A4:1: Comparison of the components of two risk assessment approaches
OIE approach Codex Alimentarius Commission (CAC) approach
Hazard identification Hazard identification
Risk Assessment
Release assessment Hazard characterisation
Exposure assessment Exposure assessment
Consequence assessment
Risk estimation Risk characterisation
Objective 8
We were asked to use a CAC approach to the Risk Assessment. This has needed to be
modified in order to address the non-public health aspects of the investigation.
Hazards have been identified then characterised. Hazard characterisation is a qualitative or
quantitative description of the severity and duration of adverse effects that may result from
the ingestion of a micro-organism or its toxin in food. A dose-response assessment should
be performed if the data are obtainable (CAC, 1999). We give a qualitative description of the
characteristics of each organism, identified as a hazard, when ingested by humans. In
addition, we describe the general characteristics of the hazard in pigs. Exposure
assessment estimates the level of microbiological pathogens or toxins and the likelihood of
their occurrence in foods at the time of consumption (CAC, 1999). For public health hazards,
whether they arise from animal health conditions or contaminants such as microbiological
organisms, the extent of actual or anticipated human exposure will only change if the risk
profile of the final (chilled) pork carcass (FCPC) changes significantly and if that change is
not combated by existing measures in the food chain after the final (chilled) pork carcass
stage. We have investigated the contribution of pork meat to the total public health exposure
to organisms that are associated with endocarditis and granulomatous lesions and carcass
microbial contamination. For hazards of concern to animal health we have investigated the
contribution that information derived from post-mortem inspection data makes to the
prevention and control of disease in the outdoor pig population. We have then characterised
Hazard identification Risk assessment
Risk management
Risk communication
FS145003 Final report ANNEX 4 v6 Page 9 of 54
the risk that exists when outdoor pigs are inspected by traditional methods. This entails the
integration of hazard identification, hazard characterisation and exposure assessment to
obtain a risk estimate (CAC, 1999). We have then compared this to the risk that exists when
outdoor pigs are inspected by a visual-only method.
Subsequent to the risk assessment we have then explored potential methods for risk
mitigation; taken a look at the impacts and at the potential benefits of implementing a visual-
only method of inspection for outdoor pigs, from non-controlled housing conditions and
drawn our overall conclusions.
RISK ASSESSMENT
Previous work
An assessment of the risk for humans associated with supply chain meat inspection – the
Danish Way (Alban et al., 2008) - did not investigate the difference in production
management systems; just that between the inspection methods. From this assessment, it
was concluded that:
the omission of incisions into the mandibular lymph nodes and the routine opening of
the heart for swine carcases do not seem to be associated with an increased risk for
human health;
there could be a positive effect on the working environment and no negative effect on
animal health.
A qualitative risk assessment (Hill et al., 2011) of the comparative risks to public and animal
health from visual inspection of indoor and outdoor pigs concluded that the risk was
negligible for all pigs. However, there were insufficient data to assess if there would be a
reduction in food-borne risk due to reduced microbiological carcass contamination. Both of
these studies utilised versions of the OIE risk assessment approach.
For a recent EFSA opinion (EFSA 2011b), on meat inspection of swine, a qualitative risk
assessment of foodborne hazards resulted in the identification of four hazards of public
health significance from the slaughter of pigs. The risk assessment was conducted using
data on prevalence on chilled carcases, incidence and severity of disease in humans, and
source attribution of hazards to pork, with the chilled carcases as the target. Salmonella spp.
were considered of high relevance currently in the EU, while Yersinia enterocolitica,
Toxoplasma gondii and Trichinella spp. were considered to be of medium relevance. The
risk reduction measures indicated for Salmonella spp. and Y. enterocolitica would also help
in the control of a number of other microbial hazards. It was recommended that inspection by
palpation and incision should be omitted in pigs subjected to routine slaughter as the risk of
microbiological contamination is higher than the risk associated with any potential reduction
in the detection of conditions currently targeted by these techniques. However; adoption of
inspection without palpation and incision is suggested as one part only of a wider
‗comprehensive pork carcass safety assurance‘ system. The scope of the work was to
evaluate meat inspection in a public health context; animal health and welfare issues were
considered with respect to the possible implications of adaptations/alterations to current
inspection methods, or the introduction of novel inspection methods that might be proposed.
Other issues that relate to the fitness of the meat for human consumption, transmissible
FS145003 Final report ANNEX 4 v6 Page 10 of 54
spongiform encephalopathies and the impact of changes to meat inspection procedures on
the occupational health of abattoir workers and inspectors, or to controls related to any
biological hazards at any meat chain stage beyond the abattoir, and the implications for
environmental protection were not included. Two methodologies (qualitative and
quantitative) were used; the former relied on expert opinion and a review of the literature,
and the latter used a three stage epidemiological modelling approach. During current
systems of meat inspection, the probability of detection of conditions is often low, particularly
for non-typical cases. This would be reduced further in the proposed modified system of pig
meat inspection although the magnitude of the difference would vary with the
disease/condition. It was recommended that this reduced detection probability could be
mitigated by follow-up inspection i.e. when abnormalities are seen with visual inspection then
further palpation and/or incision should be conducted.
FS145003 Final report ANNEX 4 v6 Page 11 of 54
Define the question
For the risk assessment the overarching questions are:
‘How would the risk profile change if fattening pigs from non-controlled housing conditions
are visually inspected, in terms of:
1. Public health
2. Animal health, and
3. Animal welfare
The impact on allocation of resources is then a consequence of risk management options
and decisions that arise from these risk assessments rather than part of the primary risk
assessment.
The fundamental question is:
What is the baseline against which any change in the risk profile is to be considered?
Hill et al. (2011) approached the problem as follows:
Indoor pigs were defined as ‗pigs raised specifically for slaughter indoors since
weaning on quality-assured farms‘. Outdoor pigs were defined as ‗pigs raised
specifically for slaughter outdoors since weaning on quality-assured farms‘.
Pigs reared indoors since weaning (with appropriate Food Chain Information (FCI)
and from integrated production systems) can be visually inspected; therefore the risk
that these pigs pose to public health and animal health and welfare must be
acceptable. If ‗outdoor pigs‘ pose the same or less of a risk, in respect of specified
hazards, then visual inspection of outdoor pigs must also be acceptable.
Their questions were, therefore:
1. What is the relative risk posed by visual-only inspection of outdoor pigs over visual-
only inspection of indoor pigs?
2. What is the absolute risk of visual-only inspected outdoor pigs?
Study FS145003 has not been designed to compare ‗indoor‘ and ‗outdoor‘ pigs; rather, it
compares the two inspection methods when applied to fattening pigs from non-controlled
housing conditions.
Definitions
The following definitions apply to FS145003 and this risk assessment:
1. Fattening pigs - ‗a pig raised specifically for slaughter.‘
2. Non-controlled housing conditions or ‗outdoor‘ – fattening pigs raised entirely
outdoors from weaning to slaughter. These are often referred to at the abattoir as
‗free-range‘ or ‗organic‘ pigs. Within this study the terms ‗outdoor‘ and ‗free range‘ are
used interchangeably and are used to refer to pigs that have been raised as
described above. As far as the authors are aware, all such commercial fattening pigs
in Great Britain (GB) are also born in non-controlled housing conditions. They need
FS145003 Final report ANNEX 4 v6 Page 12 of 54
to be distinguished from outdoor pigs that are raised outdoors and enter controlled
housing conditions at some point to be finished before they are sent to the abattoir. It
was assumed, in the design of the study, that fattening pigs raised entirely outdoors
from weaning to slaughter would be more likely to be different to pigs raised totally
indoors than fattening pigs raised partially outdoors and partially indoors; therefore
they would potentially present the greatest risk, if inspection systems were to be
changed.
3. Visual-only inspection - this is an inspection of the carcass without any palpation or
incision of any part of the carcass. It is an inspection modified from the requirements
of the European Hygiene Regulation (EC) 854/2004 (Anon., 2004b), in which the
carcases are not handled, palpated or incised, they are only examined visually (See
Table 2).
4. Traditional inspection1 - this is an inspection of the carcass where different parts of
the carcass are visualised, palpated and/or incised (See Table 2). This is derived
from the requirements of the European Hygiene Regulation (EC) 854/2004 (Anon.,
2004b).
The assumption for FS145003 is that fattening pigs from non-controlled housing conditions
inspected by traditional methods pose an acceptable risk to public health and animal health
and welfare. Thus, if the same type of pigs pose the same or less of a risk (in respect of
specified hazards) when inspected by visual-only methods, then these risks must also be
acceptable.
The first question then changes, from that asked by Hill et al., (2011) as follows:
1. What is the relative risk posed by visual-only inspection of ‘outdoor’ pigs over
traditional inspection of ‘outdoor’ pigs?
2. What is the absolute risk of visual-only inspected outdoor pigs?
There are two main criteria that will determine whether the risk profile will change with the
inspection method. These are:
1. Whether the sensitivity of detecting a condition is affected by the inspection method;
if not, then there will be no change in risk;
2. Whether the level of carcass contamination is affected by the inspection method; if
not, then there will be no change in risk.
The absolute risks remain as stated in Hill et al., (2011):
To public health – determined by the relationship between the burden of
contaminated meat entering the food chain and the rates of human illness
attributable to that contaminated pig meat.
To animal health – this may alter if there is any change in the information that is
available to be reported back to the pig farmers.
1 Meat hygiene inspector (MHI) is the UK term for Official Auxiliary
FS145003 Final report ANNEX 4 v6 Page 13 of 54
The latter will be determined by the complex relationship between the detection of a
condition and the outcome of any action taken due to the dissemination of that information in
terms of subsequent ‗cases saved‘. In addition, the absolute risk to animal health depends
on any other reporting that arises from the post-mortem inspection data e.g. the identification
and reporting of notifiable diseases.
Risk pathway
The risk pathway and, therefore the risks, on farm, during transport, ante-mortem and during
the slaughter process up until the carcass is presented for inspection are assumed to remain
constant for all outdoor pigs, regardless of the inspection method used.
In addition, the risk pathway and the processes for the final (chilled) pork carcass in the rest
of the food chain are assumed to remain constant. We are, therefore, considering at this
point only the portion of the risk pathway from slaughter to the relative risk of the final
(chilled) pork carcass.
FS145003 Final report ANNEX 4 v6 Page 14 of 54
Table A4:2: Differences in visual-only inspection compared to traditional inspection in outdoor pigs during FSA trial FS145003
Traditional Inspection Visual-only Inspection Head visual visual
Tongue visual visual
Submaxillary lymph nodes visual, incise visual Mouth visual visual Fauces visual visual Throat visual visual Lungs visual, palpate, incision¹ visual Trachea visual, incision¹ visual Main bronchi branches visual, incision visual Oesophagus visual visual Bronchial and mediastinal lymph nodes
visual, palpate visual
Pericardium visual visual Heart visual, incision visual Diaphragm visual visual Liver visual, palpate visual Hepatic and pancreatic lymph nodes
visual, palpate visual
GIT and mesenteric visual visual Gastric and mesenteric lymph nodes
visual, palpate, incision² visual
Spleen visual, palpate² visual Kidneys visual, incision² visual Renal lymph nodes incision² visual Pleura and peritoneum visual visual Genital organs visual³ visual Udder visual visual Supramammary lymph nodes
visual, incision², 3, 4 visual
Umbilical region (young) visual, palpate, incision² visual Joints (young) visual, palpate, incision² visual Based on the legal requirements contained in Regulation (EC) 854/2004.
¹When for human consumption ²When necessary ³Unless penis discarded 4Sows
FS145003 Final report ANNEX 4 v6 Page 15 of 54
Hazard Identification
This step is common to both risk assessment methodologies.
Hazard identification for Question 1:
Is the sensitivity of detecting a condition affected by the inspection method?
Previous work
This question has been considered in depth by Hill et al., (2011). A shortlist was produced of
pig diseases and conditions that could potentially be affected by a change from traditional to
visual inspection methods. It did not include conditions where detection would be unchanged
or that clearly did not pose a risk to human or animal health. A preliminary risk assessment
led to the identification of two conditions for which a change in risk to public or animal health
might potentially occur: porcine tuberculosis (pTb) and endocarditis. The conditions that
were shortlisted are shown in Table A4:3.
Table A4:3: Conditions for which detection might be affected by the inspection method and their relevance to a potential change in risk adapted from Hill et al., (2011)
Condition Preliminary risk assessment outcome
Comment
Endocarditis – usually bacterial (Streptococcus spp, Erysipelothrix rhusiopathiae, occasional parasitic or mycotic lesion)
Change (^) in human and animal health/welfare risk may arise.
Full risk assessment required because of potential serious human health issues, (although very low baseline) and lower sensitivity using visual inspection
Further investigation of outdoor-indoor pig prevalence advised; possibility that indoor prevalence is higher than outdoor. This is not an issue when comparing outdoor v. outdoor; the assumption is that inspection method will not change actual prevalence.
Necrosis in lymph nodes – possibly due to infection with Mycobacterium bovis, Mycobacterium avium, or Rhodococcus equi
Change (^) in human and animal health/welfare risk may arise.
Full risk assessment required because of the importance of Mycobacterium infections (although very low apparent prevalence) and unlikely to be detected using visual inspection
Although apparent prevalence is low in pigs; it is considered to be higher in outdoor pigs. This is not an issue when comparing outdoor v. outdoor; the assumption is that inspection method will not change actual prevalence.
Lungworm lesions No change in human health risk
Unlikely to change (^) animal health/welfare risk as initial sensitivity of detection is low anyway
Very unlikely to be detected using visual inspection
Pericarditis (acute & chronic) No change in human health risk
Unlikely to significantly change (^) animal health/welfare risk
Likely to be detected visually; possibly small reduction in sensitivity of detection through visual inspections.
Human health risk only if due to a subset combination of inadequately cooked meat and an acute case; most are not pathogens relevant to human health.
It was assumed that indoor
FS145003 Final report ANNEX 4 v6 Page 16 of 54
Condition Preliminary risk assessment outcome
Comment
prevalence was > outdoor.
Tape worms (cysticercosis) No change in human health risk
Unlikely to change (^) animal health/welfare risk as likely to be detected visually when carcass split; possibly small reduction in sensitivity of detection through visual inspections.
Human health risk is due to consumption (if meat is inadequately cooked)
In the assessment of the risk for humans associated with supply chain meat inspection – the
Danish Way (Alban et al., 2008) - the following potential hazards were considered (Table
A4:4), of which two were further assessed. These two were granulomatous lesions and
endocarditis.
Table A4:4: Conditions for which detection might be affected by the inspection method and their relevance to a potential change in risk to humans adapted from the Danish Way (Alban et al., 2008).
Mandibular lymph nodes Hearts
Granulomatous lesions due to:
Tuberculosis lesions Pericarditis
Rhodococcus equi Epicarditis
M. avium paratuberculosis Apostematous myocarditis (abscess in the heart)
Visceral larval migrans
Parasites Endocarditis
Neoplasm
Fungi
Grey text = identified but not relevant; black text = identified and considered to be relevant hazards
It has not been considered necessary to repeat hazard identification for animal and public
health conditions, given the extent of the work conducted in these two studies and the
similarities of their findings. Porcine tuberculosis (pTb) lesions are usually considered as a
subset of granulomatous lesions.
The prevalence of conditions such as endocarditis and granulomatous lesions are proxy
measures for specific organisms that may be a public health hazard. In the Danish Way
(Alban et al., 2008) these hazards were identified as Streptococcus spp. & Erysipelothrix
rhusiopathiae and Rhodoccus equi and Mycobaterium spp, respectively
Hazard identification 1PAH: the animal health associated public health hazards are,
therefore, considered to be endocarditis and granulomatous lesions to include porcine
tuberculosis lesions.
Hazard identification of conditions that might pertain to animal welfare was not part of the
Danish Way (Alban et al., 2008) risk assessment, whereas Hill et al., (2011) considered only
the welfare aspects of the diseases/conditions identified as hazards within the exposure and
FS145003 Final report ANNEX 4 v6 Page 17 of 54
consequences part of the risk assessment (all negligible to very low). Lesions of importance
for animal welfare can be identified both during ante and post-mortem inspection. The
following were identified in the ‗Overview on current practices of meat inspection in the EU‘
(Alban et al., 2011) as procedures by which animal welfare might be assessed in pigs:
Inspection of the surface of the skin as well as identification of fractured bones
(among others injuries caused during transport of the animals);
inspection of the gastrointestinal tract, the mesenterium, and the related lymph nodes
(Lnn. gastrici, mesenterici, craniales or caudales) (Gastric ulcer, peritonitis related to
hernia);
inspection and palpation of the umbilical area as well as the joints in young animals.
In case of doubt, incisions into the area around the umbilical area are made, and the
joints are opened (hernia, umbilical infection). This lesion might be considered of
relevance for animal welfare if a high prevalence is observed.
inspection of the genitalia (except from penis if it has already been condemned).
(Late pregnancy / torsion of testicle / hernia).
Not all of these will be applicable to fattening pigs (e.g. late pregnancy) and the majority are
already only assessed by visual inspection during the current traditional inspection protocol
(see Table A4:2).
The probabilities of detection of typical cases during ante and post-mortem inspection of five
welfare conditions were modelled in the external scientific report to EFSA (COMISERV,
2011) on the contribution of meat inspection to animal health surveillance in swine. These
conditions were lameness, arthritis and bursitis, tail biting and/or amputation, bruising and
skin lesions, and Dark, firm and dry (DFD) meat. The probabilities of detection did not
change significantly between conventional and visual-only inspection methods.
Hazard identification 1AW: no additional conditions have been identified as hazards for
animal welfare.
FS145003 Final report ANNEX 4 v6 Page 18 of 54
Study FS145003 Objective 3
The results from this comparison of the baseline values of the frequency and type of
conditions found using visual-only inspection and traditional inspection procedures in
fattening pigs from outdoor housing conditions, obtained from the data collected during the
field trial, help to inform:
1. whether the hazards identified in the previous work (above) are relevant to the study
situation;
2. whether additional hazards are identified, specific to the study situation.
A trial was run in one abattoir over five separate weeks during the period from the end of
November 2011 until the middle of March 2012. In this trial 11,086 carcases of fattening
pigs, from 62 batches and 12 farms, from non-controlled housing conditions were inspected
using both post-mortem inspection methods (traditional and visual-only inspection). The
type, frequency and distribution of conditions detected by each of the post-mortem
inspection methods was established and then compared. The effect of season and farm of
origin as potential confounders were investigated in the statistical analyses, as was the
effect of farm of origin as a cluster. No such effects were found. The analyses were
corrected for multiple significance testing.
What conditions in free-range pigs were observed in our study at statistically different
frequencies by the two inspection methods?
At a level of statistical significance of P < 0.00256 there were differences in the frequencies
found by the two inspection methods for eight of the categories of conditions (Tables A4:5 &
A4:6). These were milk spots, renal pathology (including kidney lesions, kidney pathology
and suspect uraemia), enteritis (including enteritis, colitis and pathology in the guts), pluck
pathology (as stated), faecal contamination of the carcass and hair contamination of the
carcass and, when analysed as absence/presence, for generalised conditions (suspect
pyaemia, suspect fever/septicaemia, oedema/emaciation and anaemia) and endocarditis.
The frequencies observed were higher with the visual method of detection for hair
contamination (visual > traditional).
The frequencies observed were higher with the traditional method of inspection for
milk spot, renal pathology, enteritis, pluck pathology and faecal contamination, and
for the absence/presence of generalised conditions and endocarditis (traditional >
visual).
FS145003 Final report ANNEX 4 v6 Page 19 of 54
Table A4:5: Descriptive analysis of the frequency of the eight conditions (with a statistically significant difference between the two inspection methods) found in pigs from non-controlled housing conditions at post-mortem meat inspection by the two inspection methods; number (n), percent of total carcases inspected (%) and 95% confidence interval (95% C.I.)
Conditions in whole carcases and offal
FSA coding of conditions Visual-only inspection Traditional inspection
N % 95% C.I.
n % 95% C.I.
Generalised Conditions Suspect pyaemia, suspect fever/septicaemia,
oedema/emaciation,anaemia
12 0.1 0.02 – 0.20
55 0.5 0.16 – 0.83
Milk Spot Milk spot 263 2.4 1.33 – 3.41
601 5.4 3.52 – 7.32
Renal Pathology Kidney lesions, kidney pathology,
suspect uraemia 448 4.0
3.28 – 4.80 798 7.2
5.87 – 8.52
Endocarditis Endocarditis 0 0 21 0.2 0.05 – 0.33
Enteritis Enteritis, colitis, pathology in the guts 22 0.2
0.97 – 0.33 123 1.1
0.75 – 1.47
Pluck Pathology Pathology in the pluck 181 1.6 0.82 – 2.44
524 4.7 3.47 – 5.98
Faecal Contamination Faecal contamination in any part of carcass/offal
353 3.2 2.16 – 4.21
545 4.9 3.53 – 6.30
Hair Contamination Hair contamination in any part of carcass/offal
1362 12.3 9.83 – 14.75
419 3.8 1.20 – 6.36
Table A4:6: Summary of the eight conditions where there was a statistical significant difference between visual-only and traditional inspection methods
Condition Mean of the difference (traditional
– visual) %
P value
Milk spots 3.21 <0.001
Renal Pathology 3.09 <0.001
Enteritis 0.99 <0.001
Pluck pathology 3.02 <0.001
Faecal contamination 1.62 <0.001
Hair contamination -8.21 <0.001
Generalised conditions <0.001
Endocarditis 0.0015
We did not expect to see a difference in detection rates for these generalised conditions
(suspect pyaemia, suspect fever/septicaemia, oedema/emaciation and anaemia) between
the two inspection methods as Meat Hygiene Inspectors (MHIs) currently use predominantly
visual inspection to identify them. On further examination of the data, the only one of the four
component conditions that had a statistically significant difference between the two
FS145003 Final report ANNEX 4 v6 Page 20 of 54
inspection methods was suspect pyaemia (absence/presence; McNemar test p=0.00018,
mean of the differences 0.65, 95% C.I. 0.23-1.1, p=0.0031). In most of the batches where
MHIs detected suspect pyaemia, there was only one positive carcass. However, there was
one batch with 11 suspect pyaemia (out of 79) positive carcases recorded and another one
with six suspect pyaemia (out of 427) positive carcases recorded. These numbers are
unexpected, especially so when the general health of pigs arriving to the abattoir is as good
as it was observed to be in the study. The Meat Hygiene Service (MHS) reported that only
0.35% of carcases slaughtered in British abattoirs were rejected as a whole (whole carcass
rejected) in 2005 (NADIS, 2012), mostly due to pyaemia, septicaemia and oedema. Pyaemia
was the major cause, responsible for 55% of the total rejection of carcases in the UK during
that year i.e. 0.19% of all pig carcases; seen in 19 in 10,000 carcases or almost two in 1000
carcases. Suspect pyaemia prevalence in carcases in abattoirs in UK observed in the British
Pig Executive (BPEX) monitoring scheme (BPHS) is lower than 1% of carcases inspected
(BPEX, 2008). In addition, in the analyses of historical data from the study abattoir the mean
prevalence of pyaemia in batches in which the condition was present in free range pigs was
only 1.1% (95% C.I. 1.0 – 1.3). In the opinion of the authors the most likely explanations for
the unprecedented numbers (over 10%) recorded at the traditional inspection point in these
two batches are due to recording error and, possibly, misclassification. This conclusion is
supported by further examination of the data. Neither ‗Generalised conditions‘ nor suspect
pyaemia are, therefore, considered to be a potential hazard. This position is supported as
Hill et al., (2011) did not include it in their first round of hazard identification.
Do they pose a potential hazard to public health?
Endocarditis cannot be detected by visual-only inspection; therefore, it has to remain as a
possible animal health associated public health hazard.
Milk spot was not considered by Hill et al., (2011) to be a hazard as it could be detected
visually, did not require palpation and incision and was not thought to be a public health
hazard when consumed. Apart from endocarditis, none of the other pathological conditions
identified above (renal pathology, enteritis, and pluck pathology) were considered in their
first round of hazard identification, with the possible exception that 'Nephropathy (abnormal
kidney)‘ would be included in our classification of ‗renal pathology‘. Although detection of
nephropathy requires both a visual and incision approach, they (Hill et al. 2011) identified no
public health risk.
A difference in the frequencies of faecal contamination recorded between the visual and
traditional inspection methods was observed in our study. It is possible that this could be
considered an additional public health hazard. It would however be most likely to be
considered as a proxy measure for microbiological contamination, which we have studied
directly in this field trial (see Hazard identification for Question 2) and so the question of
whether this is a potential hazard will be considered there.
Do they pose a potential hazard to animal health?
Although there are statistical differences between the amounts found by the two inspection
methods, with traditional inspection frequencies being higher than visual inspection
frequencies for seven of the categories of conditions investigated, this does not
automatically mean that there is a potential hazard to animal health. The difference observed
FS145003 Final report ANNEX 4 v6 Page 21 of 54
may not mean anything in terms of animal health, the disease process, the number of cases,
actual prevalence or the potential to ‗save‘ cases if control strategies are implemented
subsequent to the condition being recorded in the abattoir, i.e. the difference may not be
biologically significant, or clinically relevant.
Faecal contamination is not a condition that would have a direct or indirect relationship with
animal health. This leaves milk spots, renal pathology, enteritis, pluck pathology and
endocarditis. Although the pigs were individually inspected by both methods, the number of
pigs with a particular condition was recorded at batch level e.g. 3/50 and the frequency
calculated (%). For milk spots, renal pathology, enteritis and pluck pathology, the difference
in frequency found by the two inspection methods was calculated (traditional minus visual)
for each batch and the mean of the differences estimated. These mean differences are very
small (less than 3.5%). This, combined with the fact that for three of the conditions (milk
spots, renal and pluck pathology) there is a within-batch mean prevalence (when present) of
more than 5%, and they have a statistically significant correlation between the findings by
the two inspection methods and that for all four conditions there is a high batch level
prevalence (more than 50% of batches affected) implies that at batch level there is not a
biologically significant or clinically relevant difference between visual-only and traditional
inspection i.e. the reduced number of individual affected pig carcases found and recorded
when using visual inspection compared to traditional inspection is unlikely to have a
significant impact on the availability of relevant pathological data to feed back to the
producers for these four conditions (milk spots, renal pathology, enteritis and pluck
pathology).
Some of the differences observed within our trial between the frequencies found by visual
and traditional inspection may have been due to the total ―hands-off‖ nature of the study
design because access to the whole offal was substantially reduced. This would have
affected the ability to detect milk spot, renal pathology, enteritis and pluck pathology by
visual inspection. Even if they are not considered to be significant hazards, an improvement
in accessibility to all parts of the carcass should increase the ability to find these conditions
and decrease the differences.
Endocarditis occurs in low numbers, at a low mean prevalence within batches and a
comparatively low percentage of batches are found to be affected with the condition. In the
analysis of historical data from this abattoir the mean within-batch prevalence in batches of
free-range pigs, in which the condition was present, was 0.8%. The percentage of batches
affected with endocarditis was 3.5% (95% C.I. 2.6 – 4.4). If a condition occurs at a low
within-batch prevalence and the detection of its presence in a batch is reduced when the
inspection method is changed from traditional to visual, then this reduction in the number of
batches being classified as affected will have the greatest apparent impact on a condition
that affects a lot of batches i.e. the apparent number of affected batches will be reduced.
This may have a significant impact on the availability of relevant pathological data to feed
back to the producers and, subsequently, on animal health. Whether it actually has a
significant impact on animal health is dependent on whether producers take action to
mitigate or control the causes of the conditions in their herds after receiving such
information.
Do they pose a potential hazard to animal welfare?
FS145003 Final report ANNEX 4 v6 Page 22 of 54
None of the conditions identified in our study would have direct effects on animal welfare due
to any reduction in their identification. They may have indirect effects due to any implications
for animal health.
Hazard identification 1PAH & 1AH & 1AW: no additional animal health associated public
health hazard has been identified from our study.
No additional animal health associated animal health hazards have been identified.
No further animal health associated animal welfare hazards have been identified.
Do our study findings support the animal health associated public health hazards identified in
previous work?
The original animal health associated public health hazards that were identified in the earlier
studies were endocarditis and granulomatous lesions to include porcine tuberculosis lesions.
Endocarditis cannot be detected by visual-only inspection; therefore, it has to remain as a
possible animal health associated public health hazard. We were unable to investigate
whether there was a difference in the frequency of granulomatous lesions to include porcine
tuberculosis lesions identified by visual and traditional methods of inspection as none were
observed in the study abattoir during the study period. So, it too has to remain as a possible
animal health associated public health hazard.
Hazard identification 1PAH: the original animal health associated public health hazards
are, therefore, still considered to be endocarditis and granulomatous lesions to include
porcine tuberculosis lesions.
Hazard identification for Question 2:
Is the level of carcass contamination affected by the inspection method?
A – Identify the micro-organisms or the microbial toxins of concern with food (CAC, 1999)
Previous work
The recent EFSA opinion on the public health hazards to be covered by the inspection of
meat (swine) looks at the European Union (EU) situation as a whole (EFSA 2010b). The
BIOHAZ committee identified 15 biological hazards for which there is evidence that they
occur or may occur in pigs in Europe and that they can be transmitted via food to humans.
The main transmission pathways for Brucella suis, Erysipelothrix rhusiopathiae, Leptospirae
and Streptococcus suis were not considered to be foodborne (Anon., 2000) and so were not
included. There is a lot of uncertainty about the public health risk related to consumption of
bacteria that are resistant to antibiotics; however it was considered to be significantly lower
than the 15 pathogens listed. It was therefore concluded not to consider this characteristic of
microbiological hazards in isolation, but as one of pathogenicity attributes when ranking
them, especially for Salmonella and MRSA. A simple preliminary qualitative risk assessment
using a ranking algorithm was used to produce a ‗short list‘ for fresh (chilled) pork carcases.
Information on source attribution based on evidence, the literature and expert opinion
suggesting epidemiological links between human cases and pork, was considered as a
moderating factor in the final ranking of hazards. There was one final high risk (Salmonella
spp.) and several of a final medium risk ‐ Y. Enterocolitica*; Trichinella spp.; Toxoplasma
gondii; Sarc. suihominis and T. solium cysticercus. The latter two were excluded from further
FS145003 Final report ANNEX 4 v6 Page 23 of 54
consideration as there was no information on occurrence in carcases and human cases in
EU. The actual relevance to humans in the EU is, therefore, unknown and it was not
currently considered relevant in the EU pig population. However, they are to be monitored in
future. Those pathogens ranked as ‗low risk‘ were excluded from further consideration.
Trichinella spp. is detected by diagnostic testing that uses enzymatic digestion of muscle.
This procedure would not be altered by an alteration to the carcass inspection method. It is
not possible to transfer the micro-organism from one carcass to the other by manual
handling at inspection and so it is not further considered as a hazard relevant to our
situation. Current post-mortem inspection cannot macroscopically detect Toxoplasma gondii;
it will not be transferred by manual handling and so it too is not further considered as a
relevant hazard.
Hazard identification 2A-PHCM: this leaves the two microbial hazards identified as
Salmonella spp. and Y. enterocolitica*
*In this EFSA Opinion Yersinia enterocolitica is defined as ―...human enteropathogenic
Y. enterocolitica with biotype/serotype combinations that have their main reservoirs in pigs,
in particular biotype 4/serotype O:3, biotype 2/serotype 9, but also biotype 2/serotype O:5,
27.‖
In addition to the EFSA Opinion referred to above, there is control and surveillance of the
hygiene of the process to reduce the risk of pathogens on the meat. This includes aerobic
colony count, Enterobacteriaceae and Salmonella according to Regulation (EC) No
2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs, Annex 1, Chapter
2.1 9 (Anon., 2005).
FS145003 Final report ANNEX 4 v6 Page 24 of 54
Table A4:7: Hazard identification – conditions that detection of which could be or were affected by the inspection method and their relevance to a potential change in risk
Potential Hazard Hazard area Ref: mentioned in Comment Retain
Public Health
Animal Health
Animal Welfare
Hill et al., (2011)
Alban et al., (2008)
FS145003 field study
EFSA (2010b)
Endocarditis * * * * *
Cannot be identified by visual inspection – has to be considered a public health hazard. Not currently included in reported trends analyses for industry , therefore not considered to be highly significant for animal health.
*
Granulomatous lesions including porcine tuberculosis
* * * * None found; cannot be excluded
Perceived public health importance of Mycobacterium infections
*
Milk spots * * *
Statistically significant finding tradition > visual inspection frequency recorded for free range pigs; mean of differences very small; unlikely to be of clinical/biological significance at batch level. Can be mitigated by improving visualisation/accessibility of offal.
Renal pathology * Part *
Enteritis * *
Pluck pathology * *
Faecal contamination
* * As above – in addition, considered a proxy measure
for general microbial contamination of the carcass that has been measured directly in the study.
Hair contamination * *
Statistically significant finding visual > traditional inspection frequency recorded for free range pigs;
Generalised conditions
* * * Statistically significant finding tradition > visual
inspection absence/presence frequency recorded for free range pigs in FS145003. Considered to be an anomaly of reporting and misclassification error
Salmonella spp. * * * *
No Salmonella spp. isolated in FS145003 *
Y.enterocolitica * * * *
No statistical difference detected in frequency of isolation of Yersinia spp from carcases inspected by the two methods n FS145003
*
Total aerobic colony count and Enterobacteriaceae
* Direct measure of general microbial contamination of
the carcass: assessment of hygiene of process. *
FS145003 Final report ANNEX 4 v6 Page 25 of 54
Study FS145003 Objectives 6 & 7
The results from the microbiological checks carried out during both visual-only and traditional
inspection of carcases during the field trial are able to inform this assessment with respect to
total aerobic plate counts, Enterobacteriaceae counts and the presence of Salmonella and
Yersinia and a comparison of their frequency between the inspection methods.
This aspect of the field trial is not designed to identify additional microbiological hazards.
In the same trial as previously mentioned in one abattoir over five separate weeks during the
period from the end of November 2011 until the middle of March 2012, microbiological
checks were carried out after visual-only inspection and after traditional inspection. Carcass
sponge sampling was used as described in Regulation 2073/2005 (Anon., 2005).
Total aerobic plate counts, Enterobacteriaceae counts and culture for Salmonella were
performed on 400 swabs taken after traditional inspection and 400 after visual-only
inspection. These were taken during the second, third, fourth and fifth four weeks of the trial
between 16th January 2012 and 16th March 2012. Samples could only be taken from
batches and pigs that were expected to be slaughtered before 10am to enable despatch to
the laboratory and receipt within 24 hours. Ten farms, 44 batches and 7,931 carcases from
outdoor pigs were included in the sampling frame. Only five batches were not included due
to their late arrival at the abattoir. Seven hundred and fifty-nine swabs were cultured for
Yersinia: 379 after traditional inspection and 380 after visual-only inspection. These came
from all five weeks of the study. Twelve farms, 54 batches and 9,633 carcases from outdoor
pigs were included in the sampling frame.
Potential biases and confounders were considered during the sampling design, or accounted
and adjusted for during the statistical analysis. The analyses were corrected for multiple
significance testing and P < 0.0127 was considered to be the level of statistical significance.
There was:
no statistical difference in the mean of the log10 of total aerobic plate contamination of
carcases after the two inspection methods;
a statistically significant difference in the mean of the log10 of the Enterobacteriaceae
count when present (i.e. >0); the level of contamination of carcases was lower after
visual-only inspection compared to traditional inspection;
no statistical difference in the proportion of Yersinia contamination of carcases found
after the two inspection methods;
and, no Salmonella spp. were isolated from any sample in the study.
B – Identify other non-microbial carcass contaminants that might be affected by the
inspection method.
Carcass meat (internal) contaminants
In the aforementioned recent EFSA Opinion (EFSA 2010b), carcass meat contaminants of
public health significance, such as chemical and medicinal residues, were considered. The
CONTAM Panel considered all substances listed in Council Directive 96/23/EC and
evaluated the outcome of the residue monitoring plans for the period 2005-2009. The
FS145003 Final report ANNEX 4 v6 Page 26 of 54
individual contaminants were ranked into four categories denoted as high, medium, low, and
negligible potential concern, after consideration of a number of criteria. Although the present
meat inspection system facilitates the implementation of the sampling for such contaminants,
their presence or absence is not determined by the current inspection procedures; further
laboratory analysis is required. Issues other than those of public health significance but that
still compromise fitness of the meat for human consumption (Anon., 2004b) e.g. sexual
odour (‗boar taint‘) will also not be significantly affected by a change in inspection procedure
from traditional to visual.
Hazard identification 2B –PH CI: no hazards to public health from carcass contaminants within the carcass have, therefore, been identified.
Carcass external contaminants
The frequency of presentation of any external carcass contaminants for outdoor pigs should
be independent of the inspection method, unless there is the possibility of cross-
contamination by the handling required for traditional inspection. In the historical analysis of
conditions recorded at ante and post-mortem inspection at the study abattoir (FS145003
Objective 4), five types of contamination were recorded as post-mortem processing faults.
These were blood splash, bile, faecal, grease and hair contamination. Blood splash occurs
before or during the stunning and subsequent slaughter process when blood leaves the
blood vessels due to an excessive blood pressure or trauma of the vessels. It can be seen in
small spots or bigger infiltration of whole muscle. It is not a public health issue, just an
aesthetic observation, but may indicate deficiencies with the stunning procedure i.e. have
welfare implications. Faeces and bile contamination could lead to contamination from
bacteria within them. The faeces or bile could be from the same carcass or result in cross-
contamination from another one. Grease refers to machinery grease; although it is food-
grade it could be considered as a potential hazard. Hair contamination is probably only an
aesthetic and food quality (rather than safety) issue because pig carcases go through the
scalding tank and burner and any remaining hair should be hygienic.
Study FS145003 Objective 3
At a level of statistical significance of P < 0.00256 there were statistical differences in the
frequencies found by the two inspection methods for two of the categories of conditions that
might have some relevance to external carcass contaminants with respect to microbiological
hazards (Tables A4:5 & A4:6). These were hair contamination of the carcass and faecal
contamination of the carcass.
The frequencies observed were higher with the visual method of detection for hair
contamination (visual > traditional).
The frequencies observed were higher with the traditional method of inspection for
faecal contamination (traditional > visual).
The presence of hair contamination (but see above) and faecal contamination could
conceivably be associated with presence of microbiological organisms. It is possible that
these both could be considered an additional public health hazard, i.e. as proxy measures
for microbiological contamination and the consequent potential for cross—contamination of
carcases. These aspects are studied directly in this field trial by measuring total aerobic
FS145003 Final report ANNEX 4 v6 Page 27 of 54
plate counts and Enterobacteriaceae counts. To avoid ‗double-counting‘ in the risk
assessment they have not been considered separately from these counts.
Hazard identification 2B –PH CE: the total aerobic plate counts and Enterobacteriaceae
counts will provide direct measures for the hygiene of the process, therefore indirect
potential hazards such as hair contamination and faecal contamination are not considered
individually.
Hazard Characterisation
Hazard characterisation is: a qualitative or quantitative description of the severity and
duration of adverse effects that may result from the ingestion of a micro-organism or its toxin
in food. A dose-response assessment should be performed if the data are obtainable (CAC,
1999).
We give a qualitative description of the characteristics of each organism, identified as a
hazard, when ingested by humans. In addition, we describe the general characteristics of the
hazard in pigs.
Endocarditis in pigs
Endocarditis is an inflammation of the internal lining, or endocardium, of the heart. It can
occur after a bacterial infection elsewhere in the body. If the bacteria circulate in the blood
stream (a bacteraemia) then they may reach the heart and cause an inflammatory response
there. Often this is seen as lesions on the valves. If these lesions are seen in the pig‘s heart
then it indicates that they have been, and may still be, infected with the bacteria.
Endocarditis - Streptococcus spp. including Streptococcus suis
Streptococci are common organisms in all animals including people. They may be present
as commensal organisms or can cause a range of human infections ranging from sore throat
to severe, life threatening infection such as meningitis and septicaemia. Long term outcomes
of infection can include endocarditis, imbalance and long term deafness. Fatal cases of
S. suis are rare, but not unknown. Patients who are immuno-suppressed or have had their
spleen removed (asplenic) are known to be at greater risk from disease. Infection may,
rarely, lead to toxic shock syndrome (TSS), which is difficult to treat and can cause multi-
organ failure (Health Protection Agency (HPA) accessed July 2012
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/StreptococcusSuis/GeneralInf
ormation/)
Streptococcus suis is carried in the tonsils of pigs, and pig-to-pig spread is mainly by nose-
to-nose contact or by aerosol over short distances. It may be transmitted to the sucking
piglet from the sow or from other piglets. Streptococcal meningitis in sucking piglets is
sporadic in individual piglets. It may be worse in sucking pigs when the organism has been
introduced into the herd for the first time, or where it is secondary to infection with PRRS.
Clinical signs are quick in onset; the piglet may be found dead, convulsing, or shivering, lying
on its side and paddling, with rapid side to side eye movements (nystagmus). S. suis is
associated with a variety of other conditions including septicaemia (infection of the blood),
polyserisitis (inflammation of the lining of the abdominal and chest cavities), arthritis,
endocarditis (infection of the heart) and pneumonia. It has also been isolated from cases of
rhinitis and abortion. The pattern and relative importance of the different syndromes vary in
different countries. S. suis is sub-divided into at least 34 serotypes. They vary in their
FS145003 Final report ANNEX 4 v6 Page 28 of 54
pathogenicity and the diseases they cause, both between and within types. Some types
appear to be non-pathogenic and have been isolated mainly from healthy pigs, some are
mainly associated with lung lesions, and some have been isolated from other animal species
as well as pigs. Clinical outbreaks in pigs are usually associated with trigger factors such as
overcrowding, poor ventilation or weaning. It can be treated with penicillin.
Endocarditis - Erysipelothrix rhusiopathiae
Erysipeloid is rare; in humans it is usually a mild, but pruritic (itchy, intense burning
sensation) skin condition caused by the bacterium Erysipelothrix rhusiopathiae. The bacteria
are introduced accidentally from infected animals through pre-existing skin wounds. Human
erysipeloid is largely an occupational disease of slaughterhouse workers, agricultural
workers, and those in the meat-handling and fishing industries. Occasionally it can present
with systemic symptoms such as fever, muscle aches and headaches as well as a skin
lesion. Arthritis of the fingers, septicaemia and endocarditis are rare, but not unknown long
term effects. It can be treated with penicillin. There are also effective vaccines available to
prevent disease.
Pigs are the major reservoir. E. rhusiopathiae colonizes the pharynx of pigs and is shed in
the faeces, urine or oronasal secretions of 30-50% of healthy swine. It can also be isolated
from faeces, soil, water etc. in an infected animal's environment. Clinical presentations
include acute septicaemia and ‗diamond skin disease‘. Mortality can be quite high. Chronic
forms of infection include endocarditis and arthritis
http://www.vetmed.wisc.edu/pbs/zoonoses/Erysipelas/erysipelasindex.html.
Granulomatous lesions - Rhodococcus equi
The first case of Rhodococcus equi infection in a human was reported in 1967. While still not
commonplace, R. equi has been isolated increasingly, especially as an opportunistic
pathogen. Most human infections have been associated with immune system dysfunction,
for example due to organ transplantation or infection with the human immunodeficiency virus
(HIV). Concurrently, increasing recognition of R. equi as a pathogen has led to improved
laboratory identification of infections. Infections often manifest as pulmonary involvement or
soft tissue abscesses and they are associated with significant mortality. Treatment can be
challenging, requiring early diagnosis and prolonged combination antibiotic therapy,
sometimes in combination with surgical therapy. Necrotizing pneumonia is the most common
manifestation of R. equi infection. Extrapulmonary R. equi infections have included wound
infection, subcutaneous abscess, brain abscess, thyroid abscess, retroperitoneal abscess,
peritonitis, meningitis, pericarditis, osteomyelitis, endophthalmitis, lymphadenitis,
lymphangitis, septic arthritis, osteitis, bloody diarrhoea, and fever of unknown origin, among
others. Bacteraemia and dissemination of infection follow from the primary infection site,
which is usually the lung http://emedicine.medscape.com/article/235466-overview#a0104
R. equi is an important cause of pneumonia in foals. It can infect wild boar and domestic pigs
(Makrai et al., 2008) and is commonly found in soil. From the literature reviewed by Hill et al.,
R. equi infections do not seem to have an apparent effect on the health, welfare or
performance of pigs, being asymptomatic, i.e. there are no clinical signs. No additional
information has been found.
FS145003 Final report ANNEX 4 v6 Page 29 of 54
Granulomatous lesions - Mycobacterium spp.
Human tuberculosis (TB) caused by M. bovis cannot be distinguished from that caused by
the closely related M. tuberculosis (the human TB bacterium) on clinical signs. The course
and extent of the disease is the same, as is the treatment in most cases. Symptoms of
respiratory TB include weight loss, night sweats, fever and a persistent cough which may
contain blood or pus. The treatment of TB in people is long and involves a combination of
several drugs (http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1259151943662)
From the literature reviewed by Hill et al.,(2011) Mycobacterium spp infections do not seem
to have an apparent effect on the health, welfare or performance of pigs, being
asymptomatic, i.e. there are no clinical signs. They are considered a dead-end host (no
further transmission occurs) for M. bovis, although there is some evidence that M. avium
may be excreted in the faeces raising the possibility of pig-to-pig transmission. No additional
information has been found.
Salmonella spp.
Salmonella bacteria are widespread in human and animal populations. There are a large
(approximately 2500 strains) number of Salmonella serotypes that cause food poisoning,
typhoid and paratyphoid fevers in humans. Clinical signs of food poisoning include
diarrhoea, stomach cramps and sometimes vomiting and fever, which usually last for four to
seven days and is self-limiting i.e. it clears up without treatment. However, it can be more
serious and cause dehydration in young children, the elderly and people whose immune
systems are not working properly.
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Salmonella/
In pigs, outbreaks of septicaemic salmonellosis are rare. Salmonellosis can occur at any age
but is most common in growing pigs over eight weeks of age. Severe S. Choleraesuis
infection occurs typically at around 12 to 14 weeks. Disease is dose dependent, that is, a
relatively large number of organisms are required before clinical signs occur. The Salmonella
serotypes that are most likely to cause clinical disease in pigs are S. Choleraesuis, and
S. Typhimurium and, to a lesser extent, S. Derby. Other "exotic" salmonella serotypes may
infect pigs and be shed in the faeces for limited periods but they usually remain sub-clinical.
They may be shed in faeces for several weeks or months with no clinical disease.
S. Choleraesuis and S. Derby may be carried for long periods by sows, the former
sometimes causes clinical disease in sows (fever, depression, septicaemia, pneumonia,
meningitis arthritis and diarrhoea). They multiply mainly in the intestines of young growing
pigs but also in some sows. Pigs may become long-term sub-clinical carriers, the organisms
surviving in the mesenteric lymph nodes draining the intestine. Many such carriers do not
shed the bacteria in faeces unless they are stressed. Pigs may be intermittent or continuous
faecal shedders of other serotypes but the carrier state is usually short, weeks or a few
months and is self limiting. S. Typhimurium and S. Derby are more likely to cause milder
disease, the main sign of which is usually diarrhoea.
Yersinia spp.
In humans, yersiniosis is usually self-limiting and does not require treatment, although
antimicrobial therapy may be prescribed. Most human illness is caused by Y. enterocolitica.
Y. enterocolitica is a relatively infrequent cause of diarrhoea and abdominal pain. Clinical
signs vary with age and immune system status. Infection with Y. enterocolitica occurs most
FS145003 Final report ANNEX 4 v6 Page 30 of 54
often in young children where common clinical signs in children are fever, abdominal pain,
and diarrhoea, which is often bloody. They typically develop four to seven days after
exposure and may last one to three weeks or longer. In older children and adults, right-sided
abdominal pain and fever may be the predominant signs, and may be confused with
appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, or
spread of bacteria to the bloodstream can occur.
(http://www.cdc.gov/ncidod/dbmd/diseaseinfo/yersinia_g.htm). Infection is more common in
the winter.
In pigs, asymptomatic carriage in the tonsils is high. Clinical disease in pigs due to Yersinia
infection is extremely rare. As a cause of clinical disease it is not listed as a Veterinary
Investigation Disease Analysis (VIDA) code for Animal Health and Veterinary Laboratories
Agency (AHVLA)
Total aerobic and Enterobacteriacae counts
These do not constitute hazards in their own right. Rather they are measures of the hygiene
process on the slaughter line and the potential for cross-contamination to occur. Such cross-
contamination could have implications for the risk present, in terms of increased numbers of
carcases affected, for other microbiological agents. As such an indicator they cannot be
independently characterised.
Exposure Assessment
Exposure assessment estimates the level of microbiological pathogens or toxins and the
likelihood of their occurrence in foods at the time of consumption (CAC, 1999).
For public health hazards, whether they arise from animal health conditions or contaminants
such as microbiological organisms, the extent of actual or anticipated human exposure will
only change if the risk profile of the final (chilled) pork carcass (FCPC) changes significantly
and if that change is not combated by existing measures in the food chain after the FCPC
stage.
The exposure measured by the prevalence of each agent or condition on or in carcases at
the FCPC stage is a proxy measure for human exposure from pork meat, whereas the actual
exposure is that just prior to consumption. In FS145003 we are measuring the observed
frequency slightly earlier in the risk pathway close to the inspection points. We are assuming
that:
any further steps in the immediate pathway to the FCPC stage are independent of
the inspection method and would not result in a significant change (reduction or
increase) in prevalence of each agent or condition on or in carcases;
all processes from here up to immediately prior to consumption remain constant, i.e.
are independent of the inspection method;
the frequency of these conditions or agents found during traditional inspection of
outdoor pigs constitutes an acceptable exposure.
FS145003 Final report ANNEX 4 v6 Page 31 of 54
What is the current baseline exposure assessment with the traditional inspection
method?
What is the contribution to the actual public health exposure of organisms associated with
endocarditis and granulomatous lesions in pork meat?
Endocarditis - Streptococcus spp. including Streptococcus suis
The literature for Streptococcus suis was reviewed by Hill et al., (2011). It is found in pigs in
the United Kingdom (UK). Human infection with S. suis is rarely reported and only about 150
cases have been reported from the world literature. S. suis infection is rare among humans
in England and Wales with only two to three human cases being reported each year. The
last fatal case in the UK occurred in a farm worker in 1999, due to S. suis type 14. During
2004 a total of 112 isolates were found in pigs in England and Wales, of which 46% (51)
were S. suis type 2, the serotype most commonly associated with human infection
(http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/StreptococcusSuis/GeneralIn
formation/). People in direct contact with pigs or pig products are considered at risk. Human
infection is thought to occur mainly via cuts or abrasions when handling infected carcases.
The main transmission pathways for S. suis were not considered to be foodborne (Anon.,
2000). The bacteria are unable to survive proper cooking processes (Leps and Fries, 2009),
so the contribution to human exposure made by pork meat is considered to be negligible.
Endocarditis - Erysipelothrix rhusiopathiae
The domestic pig is the most important reservoir of E. rhusiopathiae, the causal agent of
swine erysipelas, although it does cause disease in other species (Wang et al., 2010).
Humans become infected through exposure to infected or contaminated animals or animal
products and it is considered predominantly as a disease of occupational exposure. The
main transmission pathways for E. rhusiopathiae were not considered to be foodborne
(Anon., 2000). The people with the highest risk of exposure include butchers, abattoir
workers, veterinarians, farmers, fishermen, and fish-handlers (Reboli and Farr, 1989). It is
estimated that 30–50% of healthy swine harbour the organism in their tonsils and other
lymphoid tissues. However, given that between 2001 and 2006 the Health Protection Agency
(HPA 2007) reported only nine cases of bacteraemia in England, Wales and Northern
Ireland caused by this ‗uncommon pathogen‘ and subsequently the most recent report
covering 2006 to 2010 (HPA, 2011a) reports twenty cases {from one to seven/year), the
contribution to human exposure made by pork meat is considered to be negligible.
Granulomatous lesions - Rhodococcus equi
The primary ‗at risk‘ group of humans is immunocompromised people, such as those with
HIV-AIDS or transplant recipients. However, given that between 2001 and 2006 the Health
Protection Agency (HPA 2007) reported only three cases in England, Wales and Northern
Ireland of bacteraemia caused by this ‗uncommon pathogen‘ [one in 2001 and two in 2004],
and subsequently the most recent report covering 2006 to 2010 (HPA, 2011a) reports two
cases in 2008 and one case in 2009, the contribution to human exposure made by pork
meat is considered to be negligible.
Granulomatous lesions - Mycobaterium spp.:
M. bovis was the only Mycobacteria spp. identified by Hill et al. (2011) as being of a potential
risk to humans from pigs. It has not been thought necessary to re-evaluate this, given the
short time span since the completion of their work. From the enhanced TB surveillance data
for the countries of the UK
FS145003 Final report ANNEX 4 v6 Page 32 of 54
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Tuberculosis/TBUKSurveillan
ceData/EnhancedTuberculosisSurveillance/TBEnhanced01country/ the number of human
case reports for the UK in 2010 was 8,482, a rate of 13.6 (95% C.I. 13.3 – 13.9) per 100,000
compared with 8,917 [14.4 (95% C.I. 14.1 – 14.7) per 100,000] for 2009. In 2009 there were
35 isolates of M.bovis in humans with 23 of these being in people over 65 years of age. The
likely contribution of pigs to this number of cases is negligible (Hill et al., 2011). This is re-
inforced by the fact that only 29 porcine tuberculosis cases have been found in eight million
carcases inspected in 2010 (Food Standards Agency (FSA) personal communication). In
addition, in a 13 year study only one human M. bovis case was determined to be acquired
from an animal source in the United Kingdom (de la Rua-Domenech et al., 2006).
Endocarditis and granulomatous lesions public health exposure assessment
summary
The food-borne contribution made by pork meat to human exposure to Streptococcus spp.
including S. suis is considered to be negligible.
The food-borne contribution made by pork meat to human exposure to E. rhusiopathiae is
considered to be negligible.
The food-borne contribution made by pork meat to human exposure to R. equi is considered
to be negligible.
The likely contribution of pigs to the number of cases of M. bovis in humans is negligible.
What is the contribution to the actual public health exposure of organisms associated with
carcass microbial contamination of pork meat?
Salmonella spp.
Salmonella is a major cause of food-borne illness in humans. In 2010, 9,133 human isolates
were reported to the HPA centre for Infections in England and Wales. This is a substantial
decrease from the 17,163 reported in 2001. Of these isolates, 27% were S. Enteritidis, 21%
(1959) were S. Typhimurium, 6% were typhoidal salmonellas and 46% were ‗other
serotypes‘. From the 2009 reported human isolates the rate per region varied from 11.3 –
25.3 per 100,000 of the population.
(http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Salmonella/). As with the
majority of self-limiting diseases, it is likely that this figure under-represents the total burden
of illness attributable to Salmonella spp. within the population. Farm animals and foods of
animal origin are important sources of human Salmonella infections.
How much of the human cases can be attributed to foodborne exposure from pork is not
easy to quantify it is likely to be a proportion of the S. Typhimurium cases and some of the
‗other serotypes.‘ Hill et al., (2003) estimated that the risk of illness from S. Typhimurium
originating from pig-meat (whether via cross-contamination from hands or under-cooking) is
low. The expected number of cases of S. Typhimurium originating from pig-meat per year
was estimated from the mean risk of illness per serving for each pig-meat product by each of
the two exposure routes (i.e. undercooking and cross-contamination) and the level of
consumption of those products. This gave an estimate of 1,687 cases per year in England
and Wales. When they compared the estimated expected number of cases to the actual
number of reported cases in England and Wales in 2001 (and adjusted for under-reporting
using data from the UK IID Study), it suggested that approximately 30% of all
FS145003 Final report ANNEX 4 v6 Page 33 of 54
S. Typhimurium cases are attributable to pig-meat. However, this estimate should be treated
with caution since good quality consumption data were not available. As 30% of 21% is
approximately 6-7% of the total number, if applied to the rates from 2009 this would give
rates of from less than one to two per 100,000 of the population i.e. risk is low.
The Biological Hazard Panel has assessed the public health risks from Salmonella in pigs
and the impact of possible control measures. The assessment suggested that pigs and pork
may be responsible for 10 % to 20 % of all human cases of salmonellosis in the EU in 2009,
but with differences between countries (EFSA, 2010b).
Y. enterocolitica*
Pigs are considered to be the major animal reservoir for Yersinia strains that cause human
illness, even if other animal species, e.g. cattle, sheep, deer, small rodents, cats and dogs
may also carry pathogenic serotypes. Infection can be acquired from contaminated food and
water (organisms can multiply in food at 4°C).Transmission pathways include direct contact
with infected animals; person to person spread and there is a particular association with raw
pork and pork products. Preventive advice includes the avoidance of raw or undercooked
pork
http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Yersinia/GeneralInformation/.
Y. enterocolitica is listed as an uncommon pathogen involved in bacteraemia by the HPA
and was isolated from 6 to 15 cases per year between 2001 and 2006 in England, Wales
and Northern Ireland (HPA, 2007). Y. frederiksenii, Y. intermedia, Y. pseudotuberculosis and
Y. rohdei have also been isolated on occasion. During this period (2001-2006) the HPA
recorded between 11 and 34 laboratory reports in England and Wales per year of
Y. enterocolitica. This figure was 32 in 2009 with a provisional figure of 19 reports for 2010.
(http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Yersinia/)
Based on data from the Foodborne Diseases Active Surveillance Network (FoodNet), which
measures the burden and sources of specific diseases over time, approximately one culture-
confirmed Y. enterocolitica infection per 100,000 head of population occurs each year.
(http://www.cdc.gov/ncidod/dbmd/diseaseinfo/yersinia_g.htm).
In the EU in 2007, yersiniosis was the third most frequently reported human zoonosis with a
total of 8,792 confirmed cases (EFSA, 2009a) with a notification rate of 2.8/100,000 per
head of population. Y. enterocolitica was the most common species reported in human
cases by MSs and was isolated from 93.8% of all confirmed cases. By 2010, there was a
total of 6,776 confirmed cases (EFSA, 2012) with a notification rate of 1.58/100,000 per
head of population and Y. enterocolitica was isolated from 91.0% of all confirmed cases.
Fosse et al., (2008) estimated that the mean rate of human clinical cases in Europe per
annum attributable to Y. enterocolitica was 2.8/100,000 per head of population per annum
with a median of 0.943/100,000. The likely contribution of pigs to this number of cases is not
quantified, and we consider it to be high, even though the incidence of human cases in the
UK is low.
The majority of surveys in pigs at the abattoir determine the prevalence in tonsils; however
Gürtler et al., (2005) also investigated iliocaecal lymph nodes and carcases. In a population
of fattening pigs where the prevalence of Y. enterocolitica in tonsils at the abattoir was
FS145003 Final report ANNEX 4 v6 Page 34 of 54
38.4%, the prevalence on the carcass surfaces before chilling was 0.3% and this fell to 0%
after chilling.
Total aerobic and Enterobacteriacae counts
These do not constitute hazards in their own right. Rather they are measures of the hygiene
process on the slaughter line and the potential for cross-contamination to occur. Such cross-
contamination could have implications for the risk present, in terms of increased numbers of
carcases affected, for other microbiological agents. As such an indicator, a baseline
exposure assessment cannot be independently made.
Microbiological public health exposure assessment summary
The risk of illness from S. Typhimurium originating from pig-meat (whether via cross-
contamination from hands or under-cooking) is low.
The likely contribution of pigs to the number of human cases of yersiniosis is not quantified,
and we consider it to be high, even though the incidence of human cases in the UK is low.
What is the baseline for animal health? i.e. disease prevention and control?
What contribution does information derived from post-mortem inspection data have in the
prevention and control of disease in the outdoor pig population?
Endocarditis – general
Endocarditis is not scored or reported back as a condition to producers in either the British
Pig Executive (BPEX) British Pig Health scheme (BPHS) or the Wholesome Pigs Scotland
(WPS) scheme.
Endocarditis - Streptococcus spp. including Streptococcus suis
During 2004 a total of 112 isolates were found in pigs in England and Wales, of which 46%
(51) were S. suis type 2, the serotype most commonly associated with human infection
(http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/StreptococcusSuis/GeneralIn
formation/). In the VIDA report of yearly trends for pigs between 52 to 92 cases of S. suis
were diagnosed per year from laboratory submissions in GB in the period 2004 to 2011
(http://vla.defra.gov.uk/reports/docs/rep_vida_pigs04_11.pdf).
Endocarditis - Erysipelothrix rhusiopathiae
It is estimated that 30–50% of healthy swine harbour the organism in their tonsils and other
lymphoid tissues. In the VIDA report of yearly trends for pigs between four and 21 cases of
E. rhusiopathiae were diagnosed per year from laboratory submissions in GB in the period
2004 to 2011. (http://vla.defra.gov.uk/reports/docs/rep_vida_pigs04_11.pdf).
Outbreaks of death due to endocarditis has caused 15% mortality in a population of 500
growing pigs (http://www.nadis.org.uk/bulletins/erysipelas.aspx).
Granulomatous lesions - General
Granulomatous lesions are not scored or reported back as a condition to producers in either
the BPHS or WPS scheme. In the historical analyses of FSA data from the study abattoir
such lesions were not classified as a separate category, therefore, if they did occur, they
would be part of the ‗other‘ category. No cases were recorded in the study period itself by
either method of inspection. Granulomatous lesions per se are not considered as a recorded
condition in post-mortem inspection of animals at abattoirs in UK. They are lesions
FS145003 Final report ANNEX 4 v6 Page 35 of 54
considered by MHIs to help them reach a diagnosis (e.g. TB) and are not recorded in any
official system. If such a diagnosis is reached then the information is used by the authorities
as sentinels for TB in cattle. Cattle herds on and around the pig farm will be tested.
Granulomatous lesions - Rhodoccus equi
In the VIDA report of yearly trends for pigs, no cases of Rhodococcus equi were diagnosed
per year from laboratory submissions in GB in the period 2004 to 2011.
(http://vla.defra.gov.uk/reports/docs/rep_vida_pigs04_11.pdf).
Granulomatous lesions - Mycobaterium spp:
In the VIDA report of yearly trends for pigs, between zero and three cases of tuberculosis
were diagnosed per year from laboratory submissions in GB in the period 2004 to 2011.
(http://vla.defra.gov.uk/reports/docs/rep_vida_pigs04_11.pdf). Only 29 porcine tuberculosis
cases have been found in eight million carcases inspected in 2010 (FSA personal
communication). However, there is no information available about the actual prevalence in
the pig population
Salmonella spp.
An EU-wide Salmonella baseline survey was conducted in 2008. Analyses at country-level
demonstrated a strong positive association between the prevalence of Salmonella-positive
breeding holdings and the prevalence of Salmonella-positive production holdings,
suggesting a vertical dissemination of Salmonella between the holdings. The overall EU
apparent prevalence of Salmonella-positive holdings with breeding pigs was 31.8% and
33.3% of the production holdings were estimated to be positive for Salmonella. This
prevalence varied from 0% to 55.7% among the Member States. The estimated EU
prevalence of production holdings positive for S. Typhimurium and S. Derby was 6.6% and
9.0%, respectively. In the UK the prevalence of Salmonella-positive production holdings was
44% (95% C.I. 37.8-50.9%, n=191) with a prevalence of 6.6% (5.3-7.9%) for S. Typimurium
and 11% (95% C.I. 5.3-7.9%) for S. Derby, respectively (EFSA, 2009b).
In the VIDA report of yearly trends for pigs, between 67 and 120 cases of salmonellosis due
to S. Typhimurium were diagnosed per year from laboratory submissions in GB in the period
2004 to 2011. This compares to between zero and one cases of salmonellosis due to
S. Choleraesuis and 20 to 39 cases of salmonellosis due to Salmonellae not otherwise
specified (http://vla.defra.gov.uk/reports/docs/rep_vida_pigs04_11.pdf).
Y. enterocolitica*
From 2003 to 2005 the prevalence in the tonsils of 630 pigs from 45 farms in England of
pathogenic Y. enterocolitica was 44% and Y. pseudotuberculosis was 18% with 60% of pigs
carrying enteropathogenic Yersinia. Y. enterocolitica was detected on 69% of farms and
Y. pseudotuberculosis on 78%. The prevalence of each Yersinia spp. varied by season,
region and type of management system (Ortiz Martinez et al., 2010). The prevalence of
pathogenic Y. enterocolitica has also been found to vary between countries from 93% to
32% (Ortiz Martinez P., 2010; Ortiz Martinez et al., 2011). Clinical disease in animal
reservoirs is rare. As a cause of clinical disease it is not listed as a VIDA code for AHVLA
laboratories.
FS145003 Final report ANNEX 4 v6 Page 36 of 54
In a report from EU Member States (EFSA and ECDC, 2011a), on average, 4.8 % of pig
meat units were found positive for Y. enterocolitica in the reporting group and a high
prevalence was reported by two Member States in slaughter batches of pigs.
Risk Characterisation
Risk characterisation is the integration of hazard identification, hazard characterisation and
exposure assessment to obtain a risk estimate (CAC, 1999).
Risk in a qualitative, or semi-qualitative, assessment is usually expressed in categories. In
this assessment we use a modified system from Hill et al., (2011) and define the categories
as follows:
Negligible Risk or the frequency/outcome is so low as to not merit consideration
Very low Risk or the frequency/outcome is almost negligible but cannot be excluded from consideration due to uncertainty or other extenuating circumstances
Low Risk or the frequency/outcome is small/infrequent but still worth considering intervention/mitigation
Medium Occurs frequently or associated with a modest outcome
High Occurs often and/or associated with a significant outcome
Very high Almost certain to occur and/or associated with a serious outcome
Here we characterise the baseline risk with the current traditional method of inspection for
both public health and animal health (Tables A4:11 & A4:12) and then examine if that risk
profile is likely to alter if the inspection method is visual-only as implemented in our
study/field trial.
Is there a change in the risk profile if the inspection method is changed from
traditional to visual-only?
As stated at the beginning, there are two main criteria that will determine whether the risk
profile will change with the inspection method. These are:
1. Whether the sensitivity of detecting a condition is affected by the inspection method;
if not, then there will be no change in risk;
2. Whether the level of carcass contamination is affected by the inspection method; if
not, then there will be no change in risk.
FS145003 Final report ANNEX 4 v6 Page 37 of 54
From study FS145003 we have the frequencies of the hazards by the inspection method
(Table A4:8).
Table A4:8: The descriptive analyses of the frequencies (number=n [%] and where appropriate 95% confidence interval, C.I.) found in the study abattoir in FS145003 by the two inspection methods for the hazards identified.
Hazard
Identified
Frequency n [%] and 95% C.I. by inspection method
Traditional Visual
Endocarditis (1PAH) 21 [0.2]
0.05 - 0.33
0 [0]
Granulomatous lesions to include porcine tuberculosis lesions (1PAH)
0 0
Salmonella spp. (2A-PHCM) 0 0
Yersinia spp.* (2A-PHCM) 7 [1.8]
0.8 - 3.8
5 [1.3]
0.5 - 3.1
Enterobacteriaceae 120 [30]
26 – 35
115 [29]
25 – 33
Table A4:9: Student t-test for the comparison between the two inspection methods for Enterobacteriaceae counts where Enterobacteriaceae = presence and for the log10 of total aerobic plate counts.
Inspection method Mean Difference between the
mean (95%CI)
P value
Enterobacteriaceae counts where
Enterobacteriaceae = present
Traditional -1.14 0.43 (0.22, 0.63) <0.001
Visual -1.57
log 10 of total aerobic plate count
Traditional 1.497 0.08 (-0.06, 0.21) 0.2772
Visual 1.421
How many pigs from non-controlled housing conditions are currently processed annually in
Great Britain?
It is estimated that approximately 120 commercial herds supply abattoirs with pigs finished
outdoors in the UK, with an average of 15 batches a year and approximately 220 pigs per
batch (Quality Meat Scotland (QMS), personal communication). This would lead to an
estimate of approximately 400,000 ‗outdoor finished‘ pigs processed per year. Virtually all
outdoor pig finishing units are located in England. If we assume that these figures above
have some degree of accuracy then the 11,086 trial pigs form approximately 3% of the total
annual British outdoor finished pig throughput. Hill et al., (2011) estimated that 5-10% of the
total UK pig production is reared outdoors after weaning. Slaughter statistics indicate that 7,
312, 000 head of pig were killed in 2010 (Lewis, 2010). Not all of these would be fattening
pigs, however the number of boars and sows killed is no longer available. Based on previous
FS145003 Final report ANNEX 4 v6 Page 38 of 54
years it would be between 100,000-200,000. This would give an estimate of 350,000 to
700,000 for the total annual British outdoor finished pig population.
If we assume:
700,000 ‗outdoor finished‘ pigs processed are per year;
that the frequency of the conditions found in the trial pigs is the same as in the
general population of British outdoor finished pigs (a huge assumption);
that a total ‗hand-off‘ visual-only method of inspection were implemented with a
similar visual access and line speeds to the trial abattoir, at a similar point on the line
with respect to carcass trimming and dressing procedures abattoirs;
then, based on the observed overall frequency from the study (Table A4:10), there is a
potential for the total number of undetected hearts/carcases to be as follows:
Table A4:10: The predicted guesstimates of the total annual numbers of hearts/carcases potentially missed if visual-only inspection was implemented as per the trial conditions and prevalence in all ‗outdoor finished‘ pigs was the same as per the trial conditions.
Hazard
Identified
Total number of cases potentially detected/missed by inspection method per year
Traditional Visual Potentially Missed
Endocarditis (1PAH) 1400
350 - 2310
0 1400
350 - 2310
Granulomatous lesions to include porcine tuberculosis lesions (1PAH)
2.54* 0 2.54*
Granulomatous lesions to include porcine tuberculosis lesions (1PAH)
20^ 10^ 10^
*based on 29 per 8M ^based on figures from Hill et al., 2011 for both number of cases and visual detection
The number of granulomatous lesions to include porcine tuberculosis lesions cases
potentially missed is not of an order that would change the risk profile for either public or
animal health. The number of endocarditis cases potentially missed is also not of an order
that would significantly change the risk profile for public health. The public health risk arises
from the systemic bacteraemia for which endocarditic lesions are an indicator. Systemic
involvement should be detected by visual inspection and endocarditis may be observed in
carcases in combination with other lesions that may be detected on visual inspection, thus it
is only a proportion of the endocarditis lesions potentially missed that would lead to a
carcass that would have been heat treated entering the food chain (i.e. a proportion of
1400). For example in FAO (2010), if there is evidence from the carcass that the pig had a
fever it should be condemned. Carcases with ulcerative and verrucose endocarditis with no
systemic changes may be conditionally approved and then heat treated but the heart is
condemned. If the endocarditis lesions involve fibrous tissue infiltration then the carcass can
be approved and the heart only is condemned. We do not have any data on what this
proportion might be in the UK with the current traditional inspection. We have, therefore,
taken a cautious approach, assumed that it would be 100% and designated the associated
FS145003 Final report ANNEX 4 v6 Page 39 of 54
risk as non-negligible, despite the numbers above being a worst case scenario (Tables
A4:10 & A4:11).
The number of endocarditis cases potentially missed is also not considered to be of an order
that would significantly change the risk profile for animal health. While it would have some
impact an impact on the availability of relevant pathological data to feed back to the
producers there is no evidence that currently this is either an issue of importance or that they
take action to mitigate or control the causes of endocarditis in their herds after receiving
such information. This may be due to the apparent low level of occurrence and a
corresponding lack of industry concern. In addition, both S. suis and E. rhusiopathiae cause
other clinical problems in pigs. We would not miss an increase in their prevalence if we don‘t
have endocarditis as an indicator, because an increase in the prevalence of other conditions
would act as indicators. In the historical analysis of data from the study abattoir only 3.5%
(95% C.I. 2.6 – 4.4%) of batches of free range pigs were affected with endocarditis and the
mean prevalence in the batches in which the condition was present was low at 0.8% (95%
C.I. 0.6 – 0.9%) However, we have taken a cautious approach, despite the numbers above
being a worst case scenario (Tables A4:10 & A4:12). In our field study the apparent
prevalence of endocarditis by traditional inspection at a batch level (i.e. percentage of
batches affected with the condition) was significantly higher (19.3% 95% C.I. 10.8 – 31.7)
than in the historical data analysis (3.5%, 95% C.I. 2.6 – 4.4%), although the within batch
mean prevalence was similar (1.1, 95% C.I. 0.4 – 4.2 compared to (0.8% (95% C.I. 0.6 –
0.9%). The wider 95% C.I. are due to the smaller sample size of the field study.
FS145003 Final report ANNEX 4 v6 Page 40 of 54
Table A4:11: Summary of the Risk Characterisation for Public Health for the five hazards for which detection could be or was affected by the inspection method
Identified Hazard Hazard Characterisation
[Occurrence – Severity – Fatality - Treatment]
Exposure Assessment
Amount attributable
Risk characterisation
(Baseline – current – traditional inspection)
Change in risk profile if inspection method changed to visual
Revised risk
(for visual-only inspection)
Human Human cases Public health Change Relevance Public health
Endocarditis
Streptococcus spp.
Extremely Rare – Severe - Extremely rare – Possible
NEGLIGIBLE NEGLIGIBLE Yes Unlikely VERY LOW
Endocarditis
Erysipelothrix rhusiopathiae.
Rare (occupational) – Generally mild – Extremely rare – Possible
NEGLIGIBLE NEGLIGIBLE Yes Unlikely VERY LOW
Granulomatous lesions - Rhodococcus equi
Extremely rare (opportunistic) – Severe – Likely – a challenge
NEGLIGIBLE NEGLIGIBLE Possible Highly unlikely
NEGLIGIBLE
Granulomatous lesions - Mycobacterium spp.
Extremely rare (opportunistic) – Severe – Likely – Possible, can be a challenge
NEGLIGIBLE NEGLIGIBLE Possible Highly unlikely
NEGLIGIBLE
Salmonella spp. Not uncommon - Mild to moderate – Unusual – Possible
LOW VERY LOW No N/A VERY LOW
Y.enterocolitica Uncommon – Mild to Moderate – Highly Unlikely – Self-limiting/possible
MEDIUM LOW No N/A LOW
Total aerobic and Enterobacteriaceae counts
Indicator of hygiene process rather than direct clinical relevance
N/A N/A Yes Possible Potential for reduced contamination of carcases
FS145003 Final report ANNEX 4 v6 Page 41 of 54
Table A4:12: Summary of the Risk Characterisation for Animal Health (AH) for the two major hazards for which detection could be or was affected by the inspection method
Identified Hazard Hazard Characterisation
[Occurrence – Severity – Fatality - Treatment]
Exposure Assessment
Amount attributable
Risk characterisation
(Baseline – current – traditional inspection)
Change in risk profile if inspection method changed to visual
Revised risk
(for visual-only inspection)
Pigs Animal cases Animal health
Change Relevance AH
Endocarditis
Streptococcus spp.
Mostly asymptomatic carriage – Varies – Possible –Possible
NEGLIGIBLE NEGLIGIBLE Yes Highly unlikely
VERY LOW
Endocarditis
Erysipelothrix rhusiopathiae.
Mostly asymptomatic carriage – Mild to severe – Can be high - Possible
NEGLIGIBLE NEGLIGIBLE Yes Highly unlikely
VERY LOW
Granulomatous lesions - Rhodococcus equi
Asymptomatic – N/A NEGLIGIBLE NEGLIGIBLE Possible Extremely unlikely
NEGLIGIBLE
Granulomatous lesions - Mycobacterium spp.
Asymptomatic – N/A NEGLIGIBLE NEGLIGIBLE Possible Extremely unlikely
NEGLIGIBLE
FS145003 Final report ANNEX 4 v6 Page 42 of 54
Risk assessment discussion
We have used a modified CAC risk assessment approach to assess the potential change in
risks to human (public health via a food-borne route), animal health and animal welfare of a
change in the meat inspection method, from the traditional method currently employed to a
visual-only (‗hands-off‘) methodology, for fattening pigs from non-controlled housing
management systems i.e. raised outdoors from weaning to slaughter. We have used data
from previous work, scientific literature, publically available information and our own field
study to inform the risk assessment. Based on this information we have taken a cautious
approach and considered a worse case scenario. Of the five public health hazards we have
assessed (endocarditis, granulomatous lesions, Salmonella spp., Yersinia spp., total aerobic
and Enterobacteriacae counts), only two have a revised risk on a change in inspection
method. One, endocarditis, changes from negligible to non-negligible i.e. very low, while for
the other (total aerobic and Enterobacteriacae count) it is possible that the risk of cross-
contamination between carcases is reduced.
Hill et al., (2011) determined that the risk of transferring to a visual-only system was
negligible for all pigs. They rated the risk from endocarditis to be negligible, as in their
estimate around 300-400 hearts with endocarditis would be missed per year from all pigs
both indoor and outdoor (controlled and non-controlled housing conditions) over and above
those already missed by traditional meat inspection methods. Our estimate just for outdoor
pigs is of the order of three to four times that. This may be a reflection of the uncertainty in
the estimates in both pieces of work. There is also a finding from our study data that cannot
definitively be explained: endocarditis was observed by the traditional method in our study in
almost six times as many batches when compared to the free-range pigs in the historical
data analysis from the study abattoir. This did not have a statistically significant farm
component but due to the small number of farms (12) that contributed to our study some
bias due to a ‗farm‘ influence may still exist. We cannot completely rule out the possibility of
an inspection/study bias as it was not possible to blind the inspection teams. It is however
unlikely because to make such a marked effect above the norm when there was the usual
frequent rotation of the duty on study days this would have had to apply to all those doing
the traditional inspection. There is no known seasonality for endocarditis lesions. We,
therefore, have no clear explanation why this finding was of this magnitude but it
subsequently inflates our estimate of endocarditis lesions missed per year compared to that
of Hill et al., (2011).
Despite the ‗very low‘ revised risk classification for public health attributable to endocarditis
and the slight increase in risk for visual ‗hands-off‘ inspection compared to traditional
inspection for outdoor pigs, the fact still remains that outdoor pigs from non-controlled
housing conditions present at least the same, if not less (Hill et al., 2011), of a risk than
indoor pigs from controlled housing conditions. This is supported by the findings from the
historical data analysis from the study abattoir. Here, although the differences were not
statistically significant, we found that the mean prevalence in the batches in which the
condition was present for indoor pigs was at the higher end of the values for free range pigs
(1.0%, 95% C.I. 0.9-1.1% compared to 0.8%, 5% C.I. 0.6 – 0.9%), and the percentage of the
batches affected with the condition was higher (5.2%, 95% C.I. 4.6 – 5.8% compared with
3.5%, 2.6 – 4.4%). Visual inspection is acceptable for pigs from the former type of
management systems (Anon., 2004b); therefore there is no reason relevant to the public
health risk presented to exclude the latter purely on grounds of the management system
FS145003 Final report ANNEX 4 v6 Page 43 of 54
from which they originate. This is also the case for animal health risk. Action by producers is
unlikely to be taken on the basis of information received about endocarditis lesions from
post-mortem data feedback. For these causal agents, action would be taken in response to
clinical signs in live pigs with associated production losses and their economic impact.
One of the arguments for a move from a traditional palpation and incision inspection system
to a visual-only based one is that it could reduce cross contamination of carcases that would
occur via the hands and knives of meat inspectors. This, however, is an area where
evidence is sparse and it is difficult to draw robust conclusions. Mousing et al., (1997)
suggested that the increase in the number of carcases not recorded as ‗faecal
contamination‘ in a visual-only system would lead to an increase in the number of carcases
not detected that carried Yersinia spp. or Salmonella spp. (based on extrapolation from
microbiology of gut contents) although this would be outweighed by the reduction in cross-
contamination from hazardous bacteria, particularly from the pharyngeal and pluck region.
Hamilton et al., (2002) found that on microbiological examination unseen contamination on
pre-chill carcases was at similar levels with both inspection methods. The outcomes from
our field study demonstrated that although there was a statistical difference in the number of
faecal contaminated carcases recorded by each inspection method, the mean of the
differences was very small (1.62% (95% C.I. 0.8 – 2.44%) and it was highly unlikely that this
would be of clinical significance. This was confirmed by the microbiological investigations.
No difference was found in the isolation of Yersinia spp. or Salmonella spp. total aerobic
count or the presence/absence of Enterobacteriacae; however, when present the
Enterobacteriacae count was lower on carcases that had been visually inspected than
traditionally inspected, implying less contamination. The abattoir used for the field study had
a particularly good hygiene process with considerable attention being paid to procedures on
the line to ensure this. This was the norm and not due to the presence of the study team. It is
possible that a change in the inspection method from traditional to visual would lead to a
similar result in any abattoir with a level of contamination as low as or higher than the study
premises. If the level of contamination is lower, then it could be hypothesised that the
potential for cross-contamination would be lower; however, we cannot draw that as a
conclusion from our study.
In this risk assessment we have not considered the component of public health risk that is
due to occupational exposure. This would be particularly relevant for those organisms that
are considered to be occupational hazards, i.e. S. suis and E. rhusiopathiae both of which
could be contracted by those handling and incising the hearts to examine them for
endocarditis lesions. It is theoretically possible that by moving to visual-only inspection it
would eliminate the exposure of meat inspectors to these risks; however, this is likely to
have a negligible effect on public health given the current extremely small number of clinical
cases in humans in the UK.
It is beyond the remit of this study to assess if the risk assigned to Salmonella spp. and
Yersinia spp. within this risk assessment is either acceptable or comparable with that from
fattening pigs from controlled housing conditions. References are cited in (EFSA, 2011c) that
indicate that for Yersinia, organic farming systems may have a lower within-herd prevalence
despite herd level prevalence being similar to that of conventional production units. We have
not determined the pathogenicity of the Yersinia spp. found in our field study.
FS145003 Final report ANNEX 4 v6 Page 44 of 54
It has been considered that finishers from integrated production systems that are kept
indoors from weaning will have less variation in disease pattern than finished pigs from other
types of production (Alban et al., 2008). So our study pigs were fattening pigs raised entirely
outdoors from weaning to slaughter. As far as the authors are aware, all such commercial
fattening pigs in GB are also born in non-controlled housing conditions. There are, however,
fattening pigs in the UK that are raised outdoors (non-controlled) and enter controlled
housing conditions at some point, to be finished before they are sent to the abattoir. We
have assumed in the design of the study, that fattening pigs raised entirely outdoors from
weaning to slaughter would be more likely to be different to pigs raised totally indoors than
fattening pigs raised partially outdoors and partially indoors; therefore they would potentially
present the greatest risk if inspection systems were to be changed. It could be argued that
this is not the case and that fattening pigs raised partially outdoors and partially indoors
experience the worst, rather than the best of both worlds in terms of disease status; however
the authors are not aware of any data with this level of information on origin that are
available with which to make such an assessment. This became apparent in the course of
sourcing appropriate premises in which to undertake the study. However, given the
outcomes of this risk assessment and the one by Hill et al., (2011) fattening pigs from such
outdoor-indoor/combined management systems would have to be significantly different in
terms of disease status order to present an appreciable risk.
Risk assessment conclusions
1. Five hazards that are related to public health and might be affected by the inspection
method were identified - endocarditis, granulomatous lesions, Salmonella spp. and
Yersinia spp. and the hygiene process indicators - total aerobic and
Enterobacteriaceae count.
2. The risk to public health associated with one of these hazards, endocarditis, alters
with a change in inspection method.
3. The risk to public health from endocarditis in outdoor pigs from non-controlled housing
conditions inspected by a visual-only method is higher relative to the same pigs
inspected by the traditional method (very low: negligible). The absolute risk to public
health from endocarditis in outdoor pigs from non-controlled housing conditions
inspected by a visual-only method is negligible.
4. There is some evidence from the hygiene process indicators - total aerobic and
Enterobacteriaceae count – that the visual-only method results in a lower level of
contamination of carcases than inspection by the traditional method.
5. Two hazards that are related to animal heath and subsequently their welfare that
might be affected by the inspection method were identified – endocarditis and
granulomatous lesions.
6. The risk to animal health and welfare associated with neither of these two hazards
alters with a change in inspection method.
FS145003 Final report ANNEX 4 v6 Page 45 of 54
Risk mitigation measures
From this risk assessment, based on current evidence, we do not consider that there is any
appreciable additional risk to public health, animal health or animal welfare from visual-only
inspection of fattening pigs from non-controlled housing conditions in the UK over and above
that which currently exists with traditional inspection. However, we have considered potential
mitigation measures that could be considered, if it is perceived that further additional
measures are necessary to manage any residual risk.
If endocarditis lesions are perceived to represent a residual risk then arrangements could be
made to open hearts for inspection, where it is thought to be necessary.
If granulomatous lesions are perceived to represent a residual risk then arrangements could
also be made to incise relevant lymph nodes for inspection, where it is thought to be
necessary.
The difference in the frequencies of faecal contamination recorded between the visual and
traditional inspection methods found in our field study may be explained by the positioning of
the visual-only inspection point on the line and the inability to turn the carcass by the total
―hands off‖ method used. This hypothesis is supported as there were many occurrences of
―faeces contaminations in any part except tail‖ that were recorded by the MHI at the visual
inspection point, whereas in the traditional inspection recordings they were mainly of ―faeces
contamination in tail‖. The visual inspection point was placed earlier in the line than the
traditional inspection point, which was at its usual position. Between the two there was the
opportunity for plant staff to trim the carcass. Furthermore, it is unlikely that a total hands-off
visual-only inspection, even in the usual inspection position on the line, will allow all surfaces
of the carcases to be visible. Measures such as strategically placed mirrors or systems that
rotate carcases would be needed to facilitate this.
Harmonised epidemiological indicators have been identified and have been proposed for use
for food-borne hazards to public health related to pigs and pork such as Salmonella and
Y. enterocolitica (EFSA 2011c). These should form the basis for any further risk mitigation
measures, if it is deemed necessary for these micro-organisms.
FS145003 Final report ANNEX 4 v6 Page 46 of 54
Impacts
What would be the impact of the introduction of visual-only inspection of fattening pigs from
non-controlled housing conditions in the UK on…?
Impact on public health
On the basis of the evidence available to inform our risk assessment and the previous risk
assessment by Hill et al., (2011) the impact on public health of the introduction of visual-only
inspection of fattening pigs from non-controlled housing conditions would not be detrimental.
In addition, it would be similar, for public health risks associated with endocarditis and
granulomatous lesions, to the impact if visual-only inspection of fattening pigs from
controlled housing conditions were to be introduced. For those associated with Salmonella
spp. and Yersinia spp. it would be equivalent to the current impact of traditional inspection of
fattening pigs from non-controlled housing conditions.
Impact on occupational exposure
On the basis of the evidence available to inform our risk assessment and the previous risk
assessment by Hill et al., (2011) it is theoretically possible that a move to visual-only
inspection would eliminate the exposure of meat inspectors, or others involved on the
slaughter line, to occupational hazards. In the case of the bacterial diseases, S. suis and
E. rhusiopathiae, this is likely to have a negligible impact on public health. We have not
considered the impacts on other occupational hazards such as those associated with the
use of knives, which could potentially be reduced by moving to a visual-only inspection
system.
Impact on animal health
We do not consider that, on the basis of the evidence available to inform our risk
assessment and the previous risk assessment by Hill et al., (2011) there would be any
significant impact on the animal health status of the population related to the introduction of
visual-only inspection of fattening pigs from non-controlled housing conditions. What would
be extremely important to be aware of is that it would lead to a significant change in the
baseline of the recorded MHS/FSA data. It would be necessary to ensure that anyone who is
involved in any data analysis and interpretation is aware of this change i.e. one could not
assess trends in the recorded frequency of conditions from before and after (or during) any
change-over period, as one would not be comparing like with like. For example, there is
increasing interest in using available data for surveillance purposes, or if information is
currently being fed back to producers based on the MHS/FSA data, they and their advisors
would need to be made aware that this was the case. This would also be the case if visual-
only inspection of fattening pigs from controlled housing conditions is introduced.
It is not possible to assess with any degree of certainty what impact such a change in
inspection methods would have on new disease threats. It is likely to be at least as low as
any of the identified known animal health hazards; however, it remains an unknown,
unknown. In this case (and the case of any known or re-emerging disease) it would depend
on the likelihood of missing the condition i.e. the probability that the disease causes
significant pathology in an inaccessible and/or uninspected part of the carcass that would
have been identified as being ‗different‘ or unusual enough from any currently known
pathology if it had been inspected, at a level that prompts further investigation, without
FS145003 Final report ANNEX 4 v6 Page 47 of 54
having caused a significant impact in the live animal and so escaping detection by clinical
signs, either on the production unit, during transport or at ante-mortem inspection.
Impact on animal welfare
We do not consider that, on the basis of the evidence available to inform our risk
assessment and the previous risk assessment by Hill et al., (2011) there would be any
significant impact on the animal welfare status of the population related to the introduction of
visual-only inspection of fattening pigs from non-controlled housing conditions.
Impacts on resources
There is not the scope here to complete a full resource impact assessment. On the basis of
the evidence available to inform our risk assessment, the outcomes of this risk assessment,
the previous risk assessment by Hill et al., (2011) and the experience and opinions of the
authors, the impacts on the resources required related to the introduction of visual-only
inspection of fattening pigs from non-controlled housing conditions would be no different to
those related to the introduction of visual-only inspection of fattening pigs from controlled
housing conditions. Some considerations are as follows (Table A4:13):
Table A4:13: Potential impacts on resources of the introduction of visual-only inspection for fattening pigs
Resource Potential impact of introduction of visual-only inspection
MHI time on the line inspecting The time that a MHI takes on the line to inspect a carcass is unlikely to be significantly reduced i.e. inspection is not usually the current limiting factor for line speed (ROA pers. opinion). Rotation of inspectors, as is currently the practice, will need to be maintained.
Equipment There will be a reduced resource requirement in terms of knives and the means to ensure that they are appropriate for use (clean, sharp etc.). The resources requirement for the recording of observations will not change.
Training Additional resources will be required to train existing MHIs to be aware of, competent in, change to and implement a new system. There may be a reduction in resources required to train new MHIs, as knife skills will no longer be required.
Operations Any operational/systems requirements for implementation of a change will be an initial additional resource e.g. the revision of operations manuals, SOPs, etc.
Other See Other impacts
If any additional risk mitigation measures are perceived to be required then these will have
resource implications. These might include capital expenditure within the abattoirs to install
mirrors or rotating systems; changes to slaughter house procedures such as logistics,
ordering of submissions etc, and staff deployment and/or numbers if carcases are required
to be presented to the MHIs in a different way; for example, if hearts are required to be
opened by a member of staff and then presented to the MHI for a visual inspection of the
opened heart. Any such resource implications may have economic implications for individual
premises. The resource implications will need to be carefully considered by risk managers
with respect to whether they are deemed proportionate to the apparent risk.
FS145003 Final report ANNEX 4 v6 Page 48 of 54
If endocarditis lesions are perceived to represent a residual risk then arrangements could be
made to open hearts for inspection, either for all carcases or where it is thought to be
necessary. However, given the low percentage of batches affected with the condition, the
low mean prevalence in batches in which the condition is present and the lack of use of the
current information for feedback on animal health status it is difficult to envisage what criteria
would be used, or set, on which to make a decision to identify any relevant subset. To make
a proactive decision a priori to the slaughter and inspection of a batch of pigs, the criteria
would need to be based on appropriate and relevant information on the disease
pattern/status from the production unit and/or from previous post-mortem inspection. What
would constitute such information for endocarditis remains to be determined. To make a
reactive decision during slaughter of a batch in response to increased visual evidence of
systemic bacteraemia is unlikely to be possible without an extremely flexible and adaptive
inspection system. The impacts on resources arise from the work needed to set up,
implement and maintain such systems. An increase in resources will be required, the scale
and duration will depend on the scope of the system proposed. The current system of Food
Chain Information submission would need to be adapted and optimised to achieve the
required aims.
If granulomatous lesions are perceived to represent a residual risk then arrangements could
be made to incise relevant lymph nodes for inspection, where it is thought to be necessary.
Again, given the extremely low percentage of batches affected with the condition (none in
our field study), and the lack of an appreciable animal health problem in the pig population, it
is difficult to envisage what criteria would be used, or set, on which to make such a decision.
To make a proactive decision a priori to the slaughter and inspection of a batch of pigs, the
criteria would need to be based on appropriate and relevant information: one possibility
could be an assessment based on the disease status in cattle in the area of the production
unit. The impacts on resources would be similar to those required for addressing risk
mitigation measures for endocarditis lesions.
There will also be resource implications if the use of harmonised epidemiological indicators
is required to mitigate the perceived risk due to Salmonella spp. and Yersinia spp.
Other impacts
Although the present meat inspection system facilitates the implementation of the sampling
for carcass contaminants such as chemicals, pharmaceuticals and their by-products, their
presence or absence is not determined by the current inspection procedures but by
laboratory analysis. A change from the traditional to a visual inspection system will not,
therefore, lead directly to any change in the risk profile; however, consideration must be
given to whether it would have any impact on the implementation of the sampling protocols
for carcass contaminants. Similar consideration should be given to any potential impact on
any other surveillance or survey activity that might currently fall within the possible remit of
MHIs; for example – if their skills set is changed (no knife skills required) will it preclude them
from other activities?
FS145003 Final report ANNEX 4 v6 Page 49 of 54
Benefits
The primary benefit of a visual-only system of inspection that encompassed pigs from non-
controlled housing conditions would be, in the UK, the ability to implement such an
inspection system. At present although it is theoretically possible to do so for pigs from
controlled housing conditions, in terms of the regulatory process, such systems have not
been implemented because slaughterhouses process fattening pigs from different
management systems. If some require traditional inspection and others can be inspected on
a visual-only basis, it is simpler to keep to the common process of traditional inspection.
Mousing et al., (1997) concluded that the main benefit of a visual-only inspection system for
pigs would ―...probably be a reduced level of cross-contamination with hazardous bacteria.‖
This is still a debatable point, although our field study provides some evidence for reduced
carcass contamination with Enterobacteriacae on carcases where it was present. Mousing et
al., (1997) also concluded that an indirect benefit would be a reduction in labour that could
be a resource that could be utilised elsewhere. It is not clear on what evidence this
conclusion was based.
If a visual-only inspection system could be implemented for all fattening pigs in the UK, then
the benefit would be the initiation of a methodology that could change the emphasis of
inspection and form the basis of a system that maximises aspects related to consumer
safety, in addition to providing reassurance of the use of sound hygiene processes in
production and, ultimately, food safety.
FS145003 Final report ANNEX 4 v6 Page 50 of 54
Relative risk
Figure A4:2 Public and animal health hazards that arise from animal health conditions and their relative risks comparing inspection methods
Animal health conditions identified as hazards in outdoor pig
carcasses - 1PAH
Endocarditis
Visual
Traditional
Granulomatous lesions
Visual
Traditional
Very Low
Negligible
Negligible
Negligible
FS145003 Final report ANNEX 4 v6 Page 51 of 54
Relative risk
Figure A4:3: Public health (foodborne) hazards from carcass microbial contaminants and their relative risks comparing inspection methods
Microbiological agents identified as public health (food-borne) hazards on
outdoor pig carcasses - 2A-PHM
Salmonella spp.
Visual
Traditional
Y. Enterocolitica*
Visual
Traditional
Very Low
Very Low
Low
Low
FS145003 Final report ANNEX 4 v6 Page 52 of 54
REFERENCES
All cited websites in this report were accessed in the period March – July 2012
Anon., (2000) SCVMRPH Opinion of the scientific committee on veterinary measures
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17.
FSA145003 Final report ANNEX 5 v6 Page 1 of 25
ANNEX 5
FINAL REPORT FOR PROJECT FS145003
OBSTACLES TO IMPLEMENTATION - OBJECTIVE 5
EXECUTIVE SUMMARY The aim of this work was to identify any possible obstacles that may hamper the
implementation of a risk-based visual only inspection system and to suggest appropriate
adaptations to overcome those obstacles.
We have identified ten main areas where potential obstacles to implementation may arise.
These include:
the development of (and agreement on) how to classify batches of pigs according to
risk;
how to ensure that appropriate arrangements are in place to process batches of pigs
according to their risk classification;
the resource implications in terms of alterations to plant layout, staff availability and
amendments to plant operating procedures to ensure meat quality;
maximising the visibility of the carcass and offal while minimising microbial
contamination;
the potential loss of data for animal health and surveillance purposes;
and, issues associated with change in the job, methods and responsibilities for FSA
staff.
There are adaptations that could be made to overcome most of these obstacles; some
however, will require further work and some will need to involve change management and
behavioural change; areas that are outwith the scope of this project.
We conclude that the majority of the obstacles identified are the same as those that are
expected if visual-only inspection were to be implemented for fattening pigs from controlled
housing conditions and that any adaptations required would be similar.
FSA145003 Final report ANNEX 5 v6 Page 2 of 25
Table of contents
Executive summary ............................................................................................................... 1
INTRODUCTION .................................................................................................................. 4
Objectives ............................................................................................................................. 5
Particulars of inspection during the trial ................................................................................. 5
Obstacle 1: ............................................................................................................................................. 6
Adaptation 1: ......................................................................................................................................... 6
MATERIALS AND METHODS .............................................................................................. 7
RESULTS AND DISCUSSION .............................................................................................. 7
Decision tree (flow chart) for traditional and visual-only inspection ........................................................ 7
Identification of obstacles and possible solutions (including the ones identified in the decision tree).. 12
Obstacle 2: ........................................................................................................................................... 12
Adaptation 2: ....................................................................................................................................... 12
Obstacle 3: ........................................................................................................................................... 14
Adaptation 3: ....................................................................................................................................... 14
Obstacle 4: ........................................................................................................................................... 14
Adaptation 4: ....................................................................................................................................... 14
Obstacle 5: ........................................................................................................................................... 15
Obstacle 6: ........................................................................................................................................... 15
Adaptations for 5 & 6: ......................................................................................................................... 15
Obstacle 7: ........................................................................................................................................... 16
Adaptation 7: ....................................................................................................................................... 16
Obstacle 8: ........................................................................................................................................... 17
Obstacle 9: ........................................................................................................................................... 17
Adaptations for 8 & 9: ......................................................................................................................... 17
Obstacle 10: ......................................................................................................................................... 18
Adaptation 10: ..................................................................................................................................... 18
Limitations of trial ................................................................................................................ 18
CONCLUSIONS AND RECOMMENDATIONS .................................................................... 21
Conclusions ........................................................................................................................ 21
Recommendations .............................................................................................................. 22
REFERENCES ................................................................................................................... 25
FSA145003 Final report ANNEX 5 v6 Page 3 of 25
Tables and figures
Figure A5:1: Decision tree for traditional inspection of fattening pigs in the UK ..................... 9
Figure A5:2: Decision tree for visual-only inspection of fattening pigs in the UK .................. 10
Table A5:1: Differences in visual-only inspection compared to traditional inspection in
outdoor pigs during FSA trial ............................................................................................... 11
Figure A5:3: Figurative layout of inspection, detection and recording for both inspection
methods at study abattoir .................................................................................................... 19
Figure A5:4: Bird‟s-eye schematic of the layout of inspection, detection and recording for
both inspection methods at study abattoir ........................................................................... 19
Table A5:2: The ten potential obstacles to implementation of a risk-based visual meat
inspection system for fattening pig carcases and adaptations that may be required to
overcome them. .................................................................................................................. 23
FSA145003 Final report ANNEX 5 v6 Page 4 of 25
INTRODUCTION Traditionally meat inspection performed at abattoirs consists of visual inspection, palpation
and incision of specific parts of the carcase and offal from slaughtered pigs as specified by
the Regulation (EC) 854/2004 (Anonymous, 2004b) in order to declare the meat fit for
human consumption. Such inspection is now not totally appropriate for the control of food-
borne risks to public health. Historically, meat inspection detects gross pathological lesions
in the carcase and offal from slaughtered pigs, thus enabling the detection and
condemnation of meat unfit for human consumption. As traditional inspection is restricted to
the identification of conditions and/or diseases with macroscopic signs, it excludes
microbiological food-borne hazards, such as Salmonella, Campylobacter, and Yersinia.
These potential food-borne risks for public health are not controlled by the traditional
inspection methods.
Information from farms of origin was not historically available to the official veterinarian prior
to the slaughter of the animals. Knowledge about management and other factors on the farm
of origin can give indications of the likely health status of pigs sent to the abattoir and it can
help to identify any disease or conditions in carcase and offal that might endanger public
health. Post-mortem inspection is currently (Anonymous, 2004b) part of a whole system
which includes ante-mortem inspection and the latter must include information from the farm
of origin.
The European Commission reviewed the current Meat Inspection legislation (Anonymous,
2000). They considered some alternative methods of inspection for fattening pigs that were
included in Regulation (EC) No 1244/2007 (Anonymous, 2007b). The Scientific Committee
on Veterinary Measures relating to Public Health was asked to review the current inspection
at slaughterhouses for pigs. They concluded that traditional inspection is limited in its goal to
prevent zoonotic infections in humans from fattening pigs processed in abattoirs and they
explored alternative post-mortem inspection methods. They added that, not only did
traditional inspection not prevent current food-borne risks for humans, but it could increase
the microbial risk by cross contamination of the carcases.
Abattoir meat inspection is implemented in the United Kingdom (UK) according to the
European legislation, Regulation (EC) 854/2004. Under certain conditions, fattening pigs
from controlled housing conditions in integrated production systems since weaning are only
required to be visually inspected at abattoirs (Anonymous, 2007b). This is not the case for
fattening pigs from non-controlled housing conditions; these still have to be inspected at
abattoirs by traditional methods.
The present use of farm information delivered to the Official Veterinarian (OV) in the abattoir
in the form of Food Chain Information (FCI), prior to the slaughtering of pigs, should help to
identify hazards before the carcases are on the line. Procedures to improve the detection of
specific conditions that might be at a higher risk of occurring in a particular lot coming from a
farm with a history of a condition, e.g. with a high prevalence of Salmonella, can then be
implemented for that lot. This use of FCI is a process introduced in the UK, by the Food
Standards Agency (FSA), for pigs in 1st January 2008 as required by Regulation (EC) No.
853/2004 (Anonymous, 2004a), in order to improve the quality of the ante-mortem inspection
in animals prior to slaughter. Information must be sent by producers at least 24 hours before
the arrival of the animals to the abattoir. Information regarding the farm of origin is included
FSA145003 Final report ANNEX 5 v6 Page 5 of 25
to help the OV to decide if any further inspection or tests are needed during the inspection of
animals/carcases to declare them fit for human consumption.
It is believed that there is better control of the health of the animals at farm level, if pigs are
housed in controlled conditions (Anonymous, 2011). The prevalence of certain diseases
affecting public health (such as tuberculosis (TB) or Trichinella) is also believed to be lower
in pigs from controlled housing conditions, than in outdoor pigs, as they are not exposed to
sources of disease. If this is not the case and the risk from batches of pigs raised under non-
controlled housing conditions is not higher than that of batches of pigs coming from
controlled housing conditions, then outdoor pigs can also be included in the visual-only
inspection process.
The aim of Project FS145003 was to investigate the implications of changing the inspection
method, from the traditional method to a visual-only method, for fattening pigs from non-
controlled housing conditions in the UK.
OBJECTIVES The objectives of this part of the study were:
To identify any possible obstacle, at any level, that might hamper the implementation
of visual-only inspection system for fattening pigs from non-controlled housing
systems in abattoirs.
To suggest any appropriate adaptation of the visual-only inspection that will help to
overcome the obstacles identified.
For those conditions where visual-only inspection appears to be insufficient
compared to traditional meat inspection a risk analysis approach will be carried out to
identify strategies to improve the detection level of visual-only inspection.
Particulars of inspection during the trial
The visual-only post-mortem inspection carried out during the trial is different to the
proposed visual-only inspection that would be implemented in abattoirs, if a change of
inspection method was to be applied. Due to the nature of the study, no handling of the
carcase and/or offal was permitted by Meat Hygiene Inspectors (MHIs)1 involved in the
visual-only inspection during the trial. Microbiological swabs were collected after both
inspections as part of the trial (Annex 3) so the visual-only inspection was restricted to only
visual inspection, with no handling of carcases i.e. a „hands-off‟ inspection.
The visual-only inspection proposed for future implementation (Huey, 2012) would be a form
of risk-based inspection, where:
Ante-mortem inspection would include not only an inspection of the live animals but
also the consideration of the post-mortem inspection results of previous batches of
pigs from the same source and the FCI information provided.
1 Meat Hygiene Inspectors is the UK term for Official Auxiliaries
FSA145003 Final report ANNEX 5 v6 Page 6 of 25
If the batch of pigs was classified during the ante-mortem inspection as low risk and
there was no reason to suspect that there would be conditions during the inspection
that require any further inspection i.e. Officials would not need to palpate and/or
incise any part of the carcase and/or offal during post-mortem inspection to carry out
their inspection: then the batch will undergo ONLY VISUAL INSPECTION.
If the batch of pigs was classified during ante-mortem inspection as high risk and/or
there was reason to suspect that there would be conditions that require any further
inspection i.e. Official would need to palpate and/or incise any part of the
carcase/offal during post-mortem inspection to carry out their inspection: then the
batch will undergo VISUAL, PALPATION AND INCISION INSPECTION (referred to
from here on as „further inspection‟).
For example: animals coming from batches with a high risk (e.g. a previous history of the
conditions in the abattoir) of tumours might undergo further incisions of lumps found in the
carcase by Officials to identify them as potential tumours.
One potential method of classification of batches, to enable the official inspectors to specify
the risk and therefore ensure the appropriate method of post-mortem inspection for each
batch, could be to consider two levels of risk. This is an example for illustrative purposes
only, not a recommendation.
i. Low risk: No currently recorded presence in the herd of origin of any conditions such
as abnormal high mortality, Salmonella, or any disease diagnosed or suspect in the
herd and a previously low presence/absence of post-mortem conditions identified in
the abattoir in recent slaughter batches of animals from the herd.
ii. High risk: Recorded presence in the herd of origin of any conditions such as
abnormal high mortality, Salmonella, or any disease diagnosed or suspect in the herd
and a previously high frequency of post-mortem conditions identified in the abattoir in
recent slaughter batches of animals from the herd.
For the purpose of the study, no herd categorisation according to risk was carried out during
the trial. This is an area that needs more work (Annex 4).
Obstacle 1: The development of appropriate criteria, on which relevant parties agree, in
order to classify the risk status of batches of pigs is a potential obstacle to implementation of
a risk-based inspection system.
Adaptation 1: Further work is required
We include in this report any potential obstacle to the implementation of risk-based visual-
only inspection as it would be implemented were the system to be changed. This will include
some obstacles not found during the trial as a consequence of the alterations made, but
expected to be present if the whole method was implemented i.e. including the classification
of the risk level of the batch at ante-mortem inspection.
FSA145003 Final report ANNEX 5 v6 Page 7 of 25
MATERIALS AND METHODS 1. Data sources
i. Observational data collected during the trial carried out in December 2011,
January 2012, February 2012, and March 2012 at the study abattoir. This
information includes comments given by MHIs working on the plant during the
trial.
ii. Observational experiences of the primary author (ROA) from different
abattoirs in the UK. Use of the knowledge of the layout of abattoirs visited by
the primary author (ROA) in UK and FSA inspection procedures in those
premises is used to extrapolate the observations to other premises within the
UK.
iii. Analyses of the outcomes from objectives 1 to 4 to identify those conditions
where visual-only inspection is insufficient compared to traditional inspection.
iv. Literature research on the subject to identify obstacles found in similar
situations, such as trials carried out in other countries.
2. Methods
i. Decision tree (flow-chart) of visual-only inspection compared to flow-chart of
traditional inspection for post-mortem inspection at slaughterhouse for
fattening pigs from non-controlled housing conditions.
ii. Analysis of the differences between these two procedures and the logistics
needed to put in place the alternative method (visual-only inspection).
iii. Identification of logistical issues which may jeopardise the aim of post-mortem
inspection of carcases in the slaughterhouse.
iv. Identification of potential issues affecting the likelihood of detecting conditions
in carcases of fattening pigs from non-controlled housing conditions under the
visual-only inspection.
v. Analysis of the impact for public health, animal health and welfare of those
conditions under-detected by visual-only inspection compared to traditional
inspection.
vi. Discussion of possible and practical strategies to improve the detection of the
above conditions where public health, animal health and welfare are reduced.
RESULTS AND DISCUSSION
Decision tree (flow chart) for traditional and visual-only inspection
We have drawn a decision tree for traditional inspection (see Figure A5:1), as it is currently
implemented in abattoirs in the UK for fattening pigs, and one for the alternative inspection
method as it would be if a risk-based visual inspection system (Figure A5:2) was
implemented. In the visual inspection decision tree we have identified three steps that were
not present in traditional inspection:
FSA145003 Final report ANNEX 5 v6 Page 8 of 25
- Analysis of the risk status of a batch of pigs prior to slaughter
- Further inspection could be required for certain batches (high risk pigs)
- Further need for handling of carcasses and/or offal by abattoir personnel
In order to ensure that visual inspection is successfully implemented these new procedures
would have to be addressed at each abattoir. These new procedures are the same as those
that would be expected to be required if visual-only inspection were implemented in fattening
pigs from controlled housing conditions (which is deemed acceptable in the UK but not
implemented, for logistical reasons).
We analysed the needs for these new procedures together with other issues detected during
the trial.
FSA145003 Final report ANNEX 5 v6 Page 9 of 25
Decision tree in traditional inspection
Ante mortem
Disposal
Post mortem inspection: Traditional inspection
Chillers
Disposal
Fit for slaughter
Unfit for slaughter
Unfit for human consumption
Fit for human consumption
FCI
Figure A5:1: Decision tree for traditional inspection of fattening pigs in the UK
FSA145003 Final report ANNEX 5 v6 Page 10 of 25
Decision tree in visual-only inspection
Ante mortem
Low risk
High risk
Post mortem inspection: Visual-
only inspection
Post mortem inspection:
Further inspection (V-P-I)
Fit for human consumption
Unfit for human consumption
Chillers
Disposal
Chillers
Disposal
Unfit for slaughter
Fit for slaughter
Risk status analysis based on
FCI
Unfit for human consumption
Fit for human consumption
Chillers
Chillers
Disposal
Is there any need for further handling?
Is there any need for further handling?
Yes
Yes
No
No
Plant staff corrections
Plant staff corrections
New
pro
ced
ure
Fit for slaughter
Ante mortem
Unfit for slaughterDisposal
Figure A5:2: Decision tree for visual-only inspection of fattening pigs in the UK
FSA145003 Final report ANNEX 5 v6 Page 11 of 25
Table A5:1: Differences in visual-only inspection compared to traditional inspection in outdoor pigs during FSA
trial
Based on the legal requirements contained in Regulation (EC) 854/2004.
¹When for human consumption ²When necessary ³Unless penis discarded 4Sows
Traditional Inspection
Visual-only Inspection
Head visual visual
Tongue visual visual
Submaxillary lymph nodes visual, incise visual
Mouth visual visual
Fauces visual visual
Throat visual visual
Lungs visual, palpate, incision¹ visual
Trachea visual, incision¹ visual
Main bronchi branches visual, incision visual
Oesophagus visual visual
Bronchial and mediastinal lymph nodes
visual, palpate visual
Pericardium visual visual
Heart visual, incision visual
Diaphragm visual visual
Liver visual, palpate visual
Hepatic and pancreatic lymph nodes
visual, palpate visual
GIT and mesenteric visual visual
Gastric and mesenteric lymph nodes
visual, palpate, incision² visual
Spleen visual, palpate² visual
Kidneys visual, incision² visual
Renal lymph nodes incision² visual
Pleura and peritoneum visual visual
Genital organs visual³ visual
Udder visual visual
Supramammary lymph nodes visual, incision²-4 visual
Umbilical region (young) visual, palpate, incision² visual
Joints (young) visual, palpate, incision² visual
It should be noted that, based on current evidence, we do not consider that there is any
appreciable additional risk to public health, animal health or animal welfare from visual-only
inspection of fattening pigs from non-controlled housing conditions in the UK over and above
that which currently exists with traditional inspection (Annex 4).
FSA145003 Final report ANNEX 5 v6 Page 12 of 25
Identification of obstacles and possible solutions (including the ones identified in the decision tree)
1. Changes to FCI (included as part of the current ante-mortem inspection)
As discussed earlier, the analysis of FCI as part of the ante-mortem inspection is essential if
a new method of post-mortem inspection is to be based on risk. Decisions would be made
prior to animals‟ arrival at the abattoir in order to adapt the inspection to the perceived risks
from different batches and/or farms. The analysis of FCI from different batches and/or farms,
at least 24 hours before arrival for slaughter, may lead to the conclusion that further
inspection of carcases is required, i.e. of those with a perceived higher risk of conditions
which might affect the fitness for human consumption.
FCI plays an important role in the detection of conditions/diseases during the post-mortem
inspection. Healthier animals are normally taken to the abattoir, leaving the sick ones on the
farm of origin (there is a welfare pre-requisite of „fitness to travel‟ and health, in order to be
transported and to be eligible for slaughter, respectively). Animals sent for slaughter should
appear healthy; however they may still have an underlying problem. It may be more difficult
to identify them as unfit for human consumption during post-mortem inspection, if the latter is
visual-only. When the information from the rest of the herd is available as FCI to the Official
at the abattoir, procedures might be put in place to increase the likelihood of detecting
conditions/diseases (risk-based inspection). These procedures might vary depending on the
conditions expected to be present, e.g. if the presence of clinical signs indicative of infection
with organisms known to lead to endocarditis are recorded and so endocarditis is expected
to be present or occur at a high frequency in the batches, then opening of hearts prior to the
Officials‟ post-mortem inspection may be required; or if due to prior knowledge of the history
of the herd, a high prevalence of milk spot is expected, further handling of offal by Officials
will be required to increase the likelihood of detection of the condition.
Information recorded on FCI must be complete and comprehensive to allow the Official to
take the appropriate measures. FCI should include information such as history of recent
Salmonella in the herd, any disease suffered in the herd recently, mortality rate, vaccination
status of the herd, etc. to help the Official to define the health status of the herd of origin of
the batch sent to slaughter. It might also be important to make the FCI available to the
Official with more time than the current 24 hours prior to arrival of animals to the abattoir.
This will allow the arrangement of any specific post-mortem inspection, such as slaughter at
the end of the day to avoid cross contamination of carcases when slaughtering animals
coming from a farm with history of Salmonella.
Obstacle 2: the selection of the post-mortem method has to be made prior to animals
arriving at the abattoir based on the risk of each batch.
Adaptation 2: the improvement of the availability of Food Chain Information (FCI) to allow
the Officials at the slaughterhouse to gather enough information with sufficient time to define
the risk of each batch, according to the agreed criteria, and to implement the appropriate
post-mortem method and arrangements.
FSA145003 Final report ANNEX 5 v6 Page 13 of 25
2. Changes to plant layouts and slaughtering procedures
During traditional inspection in the study abattoir (which is similar to most abattoirs in the
UK): all carcases with any conditions that need trimming and/or other process that need to
be rectified (e.g. after MHIs have identified an issue to be addressed before the carcase can
be considered as fit for human consumption) are sent to the “detention”, or “detained”. Here
plant personnel will take action and then present the carcase to an additional MHI who will
confirm that the carcase is fit and stamp it with the health mark. It will then be released to the
chillers. These detained rails have a limited capacity. The number of carcases they can take
is different in each abattoir; it was around 20 carcases in the study abattoir. Once they are
full the main slaughter line has to be stopped to allow time to clear space on the detention
rail before a new carcase can be placed on it.
How to deal with aesthetic conditions (such as hair in carcases, bruising, bite wounds, or
blood splash) should be included as part of Hazard Analysis Critical Control Point (HACCP)
plan for any plant. Different strategies may be used: trimming in the detection rail detailed
above is only one possibility. Plant operators may favour the rectification of those conditions
on the slaughter line; training expert staff in trimming them without increasing the risk of
contamination to other carcases or delaying the speed of the line, or they might manage
them during the further processing of the carcases, such as preparing meat in the adjacent
cutting plant.
It has been suggested (Anonymous, 2011) that, during the visual post-mortem inspection,
carcases suspected visually to be affected with any conditions that may classify the carcase
as unfit for human consumption should be placed on a “detention rail”. Here, further
inspection (palpation and/or incision) to confirm fitness for human consumption would be
carried out. The intention is to place them in the “detention rail” and carry out the further
inspection without causing any cross contamination to the adjacent carcasses in the
slaughter line. These methods might be safe but, in the opinion of the primary author (ROA)
not practical, or feasible, in the modern UK slaughterhouse, as the capacity of current
“detention rails” will not be sufficient for the amount of potential carcases that need further
inspection. In the author‟s opinion, those further inspections will have to occur on the
slaughter line (right after the visual inspection). Training will need to be put in place to
ensure that the risk of cross contamination to other carcases is minimised when these
inspections are done.
Aesthetic conditions will be no longer inspected by the Officials, as there is no food safety
implication. This raises a potential additional problem that may occur with the logistics within
abattoirs. Officials will stamp all carcases fit for human consumption and send them to the
chillers, but as we have explained earlier, plant staff will need to handle them to resolve the
aesthetic issues, for example they may need to trim bruising. This could be done before or
after the official post-mortem inspection. If it is done after inspection, it is possible that an
increase will be required in the capacity of chillers to keep carcases and offal in need of
further handling by plant staff. This might affect the layout of the abattoir. Affected carcases
and offal would need to be stored in chillers where practices such as opening hearts, lungs
or removing parts of carcases for aesthetic purposes (when no risk for public health has
been identified) would take place. These modifications of the layout of the abattoir would
need to be part of the plant‟s HACCP plan and the complexity will depend on each particular
abattoir.
FSA145003 Final report ANNEX 5 v6 Page 14 of 25
The layout of the slaughter line might not permit visual access to the whole carcase for a
complete visual-only inspection. This problem was observed in the study abattoir. The back
of the carcase is an area particularly difficult to access with a “hands off” system. Handling of
carcases is not specifically included in the process of traditional inspection but it is
necessary to an overall inspection; for example, opening the carcase to achieve better
inspection of the inside or turning the carcase around to inspect the back of the carcase.
During the trial in the study abattoir, visual-only inspection was located in an area of the
slaughter line where this “turning” was logistically not possible; the visual-only MHI was
unable to achieve an overall inspection, especially of the tail area. This might not be the
case for all abattoirs and would not have been the case if the visual-only inspection had
occurred at the traditional inspection point in the study abattoir. The use of tools, such as
mirrors or turning devices, has been suggested to help the visual access to the whole
carcase without handling. Further research would be necessary to study the practicability
and usefulness of different tools to improve the visual-only inspection in abattoirs in UK.
The effect of the layout of the study abattoir might have biased the results observed during
the trial. The frequency of detection of conditions identified during the visual-only inspection
might have been higher if the poor access has not impeded the visibility to the whole of the
carcase.
Obstacle 3: A potential increase in the number of carcases in need of further handling
before they are released to the chillers and the consequent resource implications, whether
that be in terms of capital investment and alterations in the layout of abattoirs, or plant staff
numbers and training.
Adaptation 3: Alterations to plant layout and staff resources to handle additional carcass
dressing will need to be plant specific.
Obstacle 4: The implementation of mechanisms to ensure that detection of conditions by
visual inspection is maximised (e.g. some parts of carcases/offal may not be accessible to
the visual inspection) and the consequent resource implications.
Adaptation 4: Additional mechanisms to ensure access and visibility to carcases and offal
will need to be plant specific. Risk managers will need to consider if the resource
implications are proportionate to the perceived risk and the potential gain. Examples include
changes to the layout of the abattoir, or plant staff tasks, such as introducing rotating tools or
mirrors to allow access to all parts of carcases/offal or the preparation of offal (opening of
hearts) prior to inspection.
3. Changes to plant HACCP and procedures
Historically, meat inspection has enabled alterations to carcases that have little impact on
the risk to public health e.g. conditions that affect the aesthetics of the carcases but are not
considered a risk for humans. If this is no longer part of the duty of the Officials from the
Competent Authority (FSA in UK), then it will become part of the food business operators‟
(FBO) responsibilities at the abattoir.
If visual-only post-mortem inspection were to be implemented at the abattoir, these
conditions might no longer be detected and resolved by Officials. In order to deal with these
aesthetic issues there would need to be further handling of carcases and offal by the
FSA145003 Final report ANNEX 5 v6 Page 15 of 25
operators. These additional procedures will need to be included in the HACCP protocol in
each abattoir. There is a potential risk of microbial cross contamination of carcases and/or
offal during these additional handling procedures by the Food Business Operator (FBO)
personnel. This would probably occur after the official inspection (Fig A5:2) and this, must be
included as an important control point for the plant HACCP plan.
Training on how to handle carcases, detect and rectify these conditions would need to be
organised and delivered by the FBO to their staff. The risks that arise from potential
occupational hazards, which currently apply to Officials, would transfer to the plant personnel
staff trained to handle the carcases and/or offal not rejected at visual-only inspection by
Officials.
Obstacle 5: The need to transfer additional meat quality responsibilities to the food business
operators to deal with all the aesthetic conditions in carcases (such as hair contamination)
that no longer fall within the Competent Authority‟s remit.
Obstacle 6: The potential for microbial cross contamination of carcases and/or offal during
the plant procedures to handle and deal with the above aesthetic conditions (after official
post-mortem inspection).
Adaptations for 5 & 6: There are no immediate solutions to these obstacles; they will be
plant-specific. FBOs will need revise their HACCP plans to address these issues.
4. Changes to data generated in the abattoir
Information collected in the abattoirs has a role in the surveillance of animal health and
welfare in UK and there is increasing interest in its use and utility. Farmers receive (or, at
least, in theory could receive) the Collection and Communication of Inspection Results
(CCIR) for all batches of pigs processed in the abattoir. This could help the farmers to
improve the health status of their herd by identifying conditions and/or diseases missed at
the farm level but identified during the ante-mortem and post-mortem inspection of the
animals.
If visual-only inspection is implemented and some conditions (regarded as low risk for public
health, such as certain parasites) are not identified and/or recorded, there is a potential for
the loss of information that currently benefits farmers and national animal health and welfare
status. This includes aesthetic conditions discussed in point 2, such as bruising, bite wounds
and blood splash. Where these are considered to be useful welfare indicators additional
effort will be required to ensure that they are still recorded.
These conditions could be identified later on by plant staff (when further handling of carcase
and offal takes place). To ensure that all post-mortem conditions (regardless of who
identified them) are recorded and information is fed back to the appropriate people, CCIR
could collect data not exclusively from the FSA records but also from the “further inspection
by plant”. These conditions might not be essential for public health but they are still
information that should be fed back to farmers/veterinarians as part of the Knowledge
Transfer, so they can be aware of the status of their herds.
FSA145003 Final report ANNEX 5 v6 Page 16 of 25
Obstacle 7: a perceived, or actual, loss of data on animal health and welfare from animals
slaughtered in the abattoir.
Adaptation 7: Further work to identify the utility and benefits of the use of alternative data
sources, such as the plant‟s own records of conditions found in the abattoir (e.g. HACCP
records), followed by the implementation of appropriate systems where relevant.
5. Lack of competence, skills and understanding of the new method of post-mortem
inspection: visual-only inspection
5.1. Meat Hygiene Inspectors (MHIs)
Meat hygiene inspectors might perceive the new system as a potential way to reduce their
work loads and subsequently lead to a loss of their jobs. Efforts must be made to ensure that
this is not the case. The new system will need to be explained; the science behind it and the
role of meat inspection should be adequately communicated to MHIs for the alternative
method.
There will be a need to retrain MHIs for the new visual-only inspection of meat. MHIs have
been carrying out traditional inspection for a long period of time and their routine (and habits)
may be difficult to modify.
Lack of observation during the visual-only inspection due to the reduction of activities and
monotony of the new system (Mousing et al., 1997) might lead to a reduction of conditions
detected by MHIs. This could be minimised by reducing the inspection period in the
slaughter line for MHIs in the rota. These rotas are individual to each abattoir, and will need
to be adjusted in each one.
There is a possible need for better communication between the inspection points for
carcases and offal during the post-mortem inspection. In visual-only inspection the detection
of several conditions in different parts of carcase and/or offal will be required to identify
carcases and offal unfit for human consumption; for example, enlargement of lymph nodes in
different parts of the carcase to identify tuberculosis (TB). In the study abattoir there was
some information missing as a consequence of the layout of visual-only inspection during
the trial. MHIs at the carcase inspection point and at the offal inspection point were located
in different positions due to spatial limitations and logistics. There was no possible
interchange of information, therefore the information was not correlated and the MHIs did not
have an overall picture of conditions found in the pig (carcase and offal). If, in the study
abattoir, only a visual-only inspection system was in place, then both MHIs would be in the
same (or close) location so information about a carcase and from the corresponding offal
could be more easily exchanged. This would help to make decisions about the outcome of
the post-mortem inspection.
To minimise this risk of missing conditions the layout of post-mortem inspection must be
adapted to the new method. This must be analysed for each abattoir (because the design of
the slaughter line and inspection points might be different to the study abattoir) to ensure
practicality and efficiency.
.
FSA145003 Final report ANNEX 5 v6 Page 17 of 25
Obstacle 8: Official inspection team - perception of possible loss of their jobs as a
consequence of new system.
Obstacle 9: Reduced awareness due to lack of experience with the new post-mortem
inspection method, insufficient communication between carcase and offal inspection points
and/or the potential for a reduction in the attention paid to the task, during post-mortem
inspection, due to the monotony of the process.
Adaptations for 8 & 9: It is outwith the scope of Project FS145003 to suggest methods of
change management and how to achieve behavioural change; however, training (and
subsequent auditing) of all of the Official inspection team involved with the new system will
be needed to ensure an adequate understanding of it and to maintain a high standard of
communication and service.
5.2. Official Veterinarians
With traditional inspection, ante-mortem inspection was primarily used to assess if animals
that arrived at the abattoir were fit for slaughter; to search for any clinical signs of any
disease and to check that there were no welfare issues, either due to transport or arising
from the farm of origin.
If a new or revised risk-based inspection is to be applied, the OVs must be trained in any
new requirements that are needed to carry out risk-based categorisation of pig batches,
using FCI and previous data (conditions found in previous batches from the same farm). This
is required to ensure that the decisions, on which inspection should be applied, are made in
a standardised, consistent manner.
This means that the FCI must be complete and available for assessment at least 24 hours
before arrival, but preferable earlier than that. This will allow Officials to ensure that the
logistical issues are addressed and they are ready to undertake the appropriate inspection.
The role of FCI and ante-mortem inspection is crucial. Animals sent to the abattoir might
appear healthy, so FCI from the farm of origin may help to assess the real health status of
the farm and detect the hidden presence of some subclinical conditions, which might make
the meat from those animals unfit for human consumption, regardless of the result of ante-
mortem inspection at the abattoir. The quality of FCI must be assessed to ensure that the
data provided by producers are comprehensive and suitable for the purpose of ante-mortem
inspection. There may need to be training for producers on what information is needed for
FCI. The FCI provided may need to be adapted and/or revised. FCI needs to include further
information from the herd of origin, such as recent diseases observed in the herd
(Salmonella, Erysipelas...), any conditions observed in the herd (such as lameness),
abnormal high mortality, vaccination strategy or any management details that might help
Officials to determine the health status of the herd of origin. This would be necessary to
predict the likelihood of certain conditions (or take extra precautions to avoid cross
contamination, e.g. in case of potential Salmonella presence in pigs sent to slaughter when
animals come from a farm with recent history of Salmonella) during the post-mortem
inspection, such as higher prevalence of pleurisy, Erysipelas-like lesions, or arthritis.
FSA145003 Final report ANNEX 5 v6 Page 18 of 25
If the FCI was available to Officials with more time than is currently required, it would be
helpful. The appropriate time period required would need to be investigated and optimised; it
has been suggested that, ideally having it a week prior to the arrival of the batch, would be of
use. Information from the actual batch to be sent to the abattoir might be unknown (as
management in the farm might be unsure of the specific batch to be sent) but information
regarding the herd of origin is known and of great importance for the Officials. Information
from the FCI and post-mortem data from previous batches received in the same abattoir,
collected and kept by the FSA will need to be used for decision-making. FSA could then
make any logistical arrangements in advance; for example, the availability of additional staff,
re-arrangement of slaughter strategies (e.g. pigs coming from farms with a history of
Salmonella to be killed at the end of the day or in a specific day of the week) or any other
decision to enhance the efficiency of the post-mortem inspection (to maintain the safety of
the meat produced in the abattoir) and to minimise the cross-contamination of carcases
during the process.
This refined approach to ante-mortem inspection may also be important to identify any
animal health or welfare problem at the farm, which, with traditional inspection, would have
been identified later on during the post-mortem inspection. One of the concerns when
changing to visual-only inspection is that diseases such as TB might be missed. If suitable
predictive risk factors can be determined through appropriate studies, then animals at a
higher risk of being infected, e.g. with TB, might potentially be identified during the ante-
mortem inspection of FCI.
Obstacle 10: A perceived, or actual, decrease in the quality of the Official Veterinarian
work, such as identification of high risk batches in need of a post-mortem inspection with
inclusion of further incision of palpation, due to the lack of experience with the new system.
Adaptation 10: It is outwith the scope of Project FS145003 to suggest methods of change
management and how to achieve behavioural change; however, training (and subsequent
auditing) of all FSA personnel involved with the new system will be needed to ensure an
adequate understanding of the concepts and responsibilities that are involved and so to
maintain a high standard of service.
Limitations of trial
The recording of the conditions was not exactly the same in the traditional system (touch
screen) and visual-only system (spreadsheet) during the first pilot week of the trial, therefore
the visual-only spreadsheet was amended to reflect the same conditions as in the traditional
inspection. During the first week these missing conditions in the spreadsheet were recorded
by MHIs as “other” (as requested) until amended spreadsheets were created and circulated
for the following weeks.
At the study abattoir, during the traditional inspection, conditions were detected at two points
on the slaughter line (Figure A5:3 & A5:4) and identified using plastic markers attached to
the carcase. These conditions were not recorded. In order to speed up processing on the
line, an FBO operative between the first traditional inspection and final carcase
inspection/health marking would remove conditions such as hair contamination. Carcases
found to be free of abnormalities at the second traditional inspection point, including some
where conditions had been rectified (i.e. some hair removal, stripping of pleura, peritoneum)
FSA145003 Final report ANNEX 5 v6 Page 19 of 25
went along the main rail for further processing (no further inspection). Any carcass not
stamped as fit for human consumption at the second inspection point would be sent to the
„detain‟ rail, where further rectification and trimming could take place. Any carcase rejection
conditions were recorded at the end of the detained line. These conditions are, therefore,
recorded in the system. There were two points where rectification could have been
performed before this inspection and recording process.
For logistical reasons, during the trial at the study abattoir, the visual-only inspection point for
the carcases and the recording of the abnormalities seen had to be positioned at the point of
the 1st traditional MHI inspection. This was before any rectification or trimming process.
There will, therefore, be a higher frequency of recording of certain conditions, such as hair
contamination, by visual-only inspection compared to traditional inspection. It might seem,
that visual-only inspection is able to detect a greater number of these conditions, but this
would be an incorrect assumption; usually those conditions were detected, resolved but
never recorded.
Figure A5:3: Figurative layout of inspection, detection and recording for both inspection methods at study
abattoir
Visual Only Inspection(Recorded)
2. Traditional Inspection(no recording)
1. Traditional Inspection(Recorded)
Detention Rail
Offal inspection(recorded)
Some rectification
Rectification
PigFlow
3. Traditional InspectionNo recording
Figure A5:4: Bird‟s-eye schematic of the layout of inspection, detection and recording for both inspection
methods at study abattoir
Visual Inspection of Carcase including recording of any conditions seen
Traditional First Inspection of Carcase (no recording here)
Removal of conditions such as hair and pluerisy by FBO operative (no
recording here)
Final Inspection and health marking of carcase or send
carcase for further rectification
Recification of carcase (including recording of conditions that have
gone down the detained line)
FSA145003 Final report ANNEX 5 v6 Page 20 of 25
The role of the plant personnel positioned between the two points of inspections may need
some clarification: this operator had a role prior to the start of the trial in the study abattoir.
This operator removed any aesthetic conditions (mainly hair left on the carcases) to improve
the presentation of the carcase. They did not remove any conditions that affect the fitness of
the carcases for human consumption, so the final MHI carrying out the traditional inspection
was presented with all conditions affecting the safety of the meat.
The effect of this positioning can be seen in the outcomes from the field trial; for example, in
the visual-only inspection many occurrences of “faeces contaminations in any part except
tail” were recorded. This was due to no visual access to the back of the carcass; whereas in
the traditional inspection recordings are mainly of “faeces contamination in tail”. Any other
contamination (apart from tail) had been identified by the first MHI (at the visual-only and 1st
traditional inspection point) and dressed by the plant staff before the final MHI at the
traditional inspection point; therefore they were not recorded in the system. Contamination in
the tail area has not been detected by first MHI (and similarly at the visual-only point) and, as
a result it was not addressed before the final MHI‟s traditional inspection; hence, it is
recorded in the system.
We also noticed that there could be another reason as to why there was a higher prevalence
of hair recorded on carcases at visual inspection than at the traditional inspection. When
conducting traditional inspection, an MHI will usually have a routine e.g. incise the sub
maxillary lymph nodes first and then visually work their way up the carcase. It was noticeable
that, when conducting the visual inspection, the MHI tended to focus more at eye level. This
could possibly lead to more incidences of hair contamination being recorded.
In addition, we noticed during the field trial that there was a difference in how different MHIs
record certain conditions, or more specifically, the location of the conditions. For example,
conditions that were located in a small part of the carcase could be recorded either under the
specific area (such as „bile in belly‟) or under a general area (such as „bile in trim‟). During
the sampling and recording of the trial it was observed that it depended on the person. Some
of the MHIs were locating these conditions mostly in trim, and other MHIs were more precise
in the location. Both recording systems are fine but may interfere with any comparison of the
similarity or difference in the identification of conditions between visual-only and traditional
inspection methods. This problem was considered during the condition analysis (Objectives
1, 2, and 3) and resolved. Conditions were regrouped accordingly to the type of conditions
and not to the location of conditions. Once this was done, the inspection bias was controlled.
It will be essential to train, audit, assess, validate and evaluate the new inspection method
when implemented to ensure that it is applied consistently by all official food safety
personnel.
During the trial MHIs were not allowed to palpate or incise any carcass during the process of
the inspection. In theory, if visual-only inspection were implemented for outdoors pig
carcasses in UK abattoirs, palpation and incision of any part of the carcass will be
acceptable whenever the Officials suspect a condition that will need further investigation.
There were a few occasions during the field trial where the MHIs mentioned the fact that
he/she would progress to palpate and/or incise a specific area of the carcass after
suspecting a condition; for example, arthritis of the joints or to differentiate an abscess from
a tumour. As explained, no such further inspection took place during the trial. The outcomes
FSA145003 Final report ANNEX 5 v6 Page 21 of 25
of the trial may not, therefore, reflect the reality of a visual & risk based system. It is probable
that the visual-only system as implemented during the field study is a “worst case scenario”
for the detection and observation of conditions in pig carcasses i.e. the potential of a visual &
risk based inspection system to detect conditions in pig carcases will be greater. However, in
the trial, one of the objectives was to compare the microbiological contamination due to
handling (palpation and incision) of carcasses during the traditional inspection and during the
visual-only inspection, in order to investigate whether contamination is lower when visual-
only inspection was implemented. The outcomes of this investigation may potentially reflect
a better situation than would exist in a visual & risk based inspection system, especially if
non-food safety trimming is carried out later by plant staff (ANNEX 3 & 4).
CONCLUSIONS AND RECOMMENDATIONS Conclusions
We have identified ten main areas where potential obstacles to the implementation of a risk-
based visual inspection system for fattening pigs may occur (Table A5:4). Adaptations
should be possible to overcome all of them; however further work may be required. Specific
areas include:
1.1. Certain lack of competence, skills and understanding of the new method of
post-mortem inspection (visual-only inspection) is expected. Training of all FSA
personnel for the new visual-only inspection is required and should suffice to
overcome this obstacle; to include subsequent audit, evaluation, inter and intra-
operator validation and revision of training and methods.
1.2. Use of tools might be needed to help Officials to carry out a whole carcase
visual inspection. These tools might be a rotated system or mirrors (so the back
of the carcase will be accessible to the visual inspection).
1.3. It is advised (EC, Anon. 2011) that all carcase handling and trimming by plant
staff, such as removal of tumours, should be done in a detained area to avoid
any cross contamination to other carcasses: however, the difficulty of such a
procedure is understood. It is mainly due to the busy nature and high speed of
the slaughter line combined with the number of carcases that are expected to
be detained, which is high. It could lead to delays and associated costs. This
could be partly solved if abattoir personnel are deployed in those detain rails
permanently and routinely perform these tasks. Alternatively they could be
sited on the line near the visual inspection point with adequate training to
minimise cross contamination between carcases.
1.4. Animal health and welfare associated information from carcases could be
collected with different methods that are already in place in some abattoirs,
such as the British Pig Health Scheme (BPHS) inspections; or new methods,
such as information from further inspection done by the plant. The return of this
information to producers is relevant for animal health and indirectly relevant for
public health as it can be used by farmers to improve their herd health status.
FSA145003 Final report ANNEX 5 v6 Page 22 of 25
1.5. The result from the microbial study (objectives 1, 2, and 3 of Project FS145003)
could be used as the baseline recommended by the Scientific Committee
(Anonymous, 2000) for the study abattoir before introducing the new system.
Each abattoir will require a baseline to be established via a microbiological
survey of an appropriate design.
1.6. Revision of current HACCP plans will be needed in abattoirs to ensure that all
requirements necessary for the implementation of visual-only inspection are in
place and implemented to the relevant standards: auditing of all HACCPs in all
abattoirs slaughtering fattening pigs will be required. Again, these HACCP
plans must be individual for each abattoir.
The goal of modern meat inspection is to minimise the food-borne risk for humans
(Anonymous, 2011) (i.e. Food Safety). It is commonly accepted that it is not possible to
reduce the risk to zero; there will always be certain conditions missed by any method of
inspection. The impact of such omissions will be considered in the report for Objective 8.
Recommendations
A list of recommendations for practices that could be included in the abattoirs once the
visual-only inspection is applied is as follows:
i. Availability of the FCI in sufficient time to allow risk management decisions to be
made and the logistics to be organised, prior to the arrival of pigs for slaughter, is
essential. The FCI might contain information from the whole herd, as specific batches
to be sent to the abattoir might be unknown at the point of information submission.
ii. Information in the FCI should include the recent history of the herd. This should
include diseases and conditions of interest, such as Salmonella, or Erysipelas,
vaccination strategies, and welfare indicators e.g. lameness, tail biting) mortality rate
etc.
iii. Information of post-mortem inspection from previous batches killed at the same
abattoir from the same farm should be available and used by Officials.
iv. Officials at the abattoir should use the information from both the FCI and previous
post-mortem inspection results from each herd to categorise the batches of pigs prior
to arrival at the abattoir according to risk. This will enable the allocation of
appropriate resources to improve the quality and efficiency of the post-mortem
inspection and maintain the safety of the meat produced.
v. Re-arrangement of slaughtering strategies could include the slaughtering of high risk
batches (such as pigs coming from farm with a recent history of Salmonella) at the
end of the day, with a gap between previous batches (to minimise potential cross
contamination to low risk batches) or even in a particular day of the week; it may be a
pre-requisite that hearts are opened prior to post-mortem inspection in the line (e.g.
in cases of recent history of high prevalence of endocarditis from batches coming
from the same farm); extra plant staff in the line to trim conditions such as pleurisy
without disturbing the speed of the line and the work of the FSA inspectors if
likelihood of presence of pleurisy is expected to be high.
FSA145003 Final report ANNEX 5 v6 Page 23 of 25
vi. Use of any tool available to allow access to the whole carcase (included the back of
the carcase) for the visual inspection, such as mirrors, rotating devises or inspectors
at both sides of the line. Alternatively, allow handling of carcases/offal when
necessary, e.g. handling of offal in batches with recent history of high prevalence of
milk spot, to improve the detection of milk spot.
vii. Communication with the FBO if high risk batches are expected to be slaughtered at a
particular day or time, allowing the abattoir management team to allocate staff and
resources to manage the potential increase of procedures such as preparation of
carcases/offal prior to official post-mortem inspection, trimming, detection of carcases
or further handling of carcases during the further preparing of the meat before
dispatch.
viii. Officials should be allowed minimal handling of carcases if the visual access to the
whole carcase/offal is impeded and not resolved with any alternative method. The
visual inspection of carcases/offal must be comprehensive and complete to ensure
the efficiency of the visual-only inspection. This additional handling must be kept to
the minimum and only when visual access is not possible by any other means.
ix. MHIs should be authorised to carry out minimal incision of carcases/offal when any
condition/pathology is suspect and require the incision for confirmation, such as
abscess. The process must be kept to the minimal and hygiene must be ensured to
avoid any cross contamination to other parts of the carcase/offal or adjacent
carcases/offal.
x. Any of the above should be based on appropriate evidence and agreed a priori by
risk managers and the industry to ensure that any mitigation measures and the
consequent resource implications are proportionate to the perceived/apparent risk.
Table A5:2: The ten potential obstacles to implementation of a risk-based visual meat inspection system for
fattening pig carcases and adaptations that may be required to overcome them.
Potential Obstacles Potential Adaptations
1. The development of appropriate criteria, on which relevant parties agree, in order to classify the risk status of batches of pigs is a potential obstacle to implementation of a risk-based inspection system
Further work is required to develop agreed protocols for the classification of batches of pigs according to the perceived or apparent risk to public health
2. The selection of the post-mortem method has to be made prior to animals arriving to the abattoir based on the risk of each batch
The improvement of the availability of Food Chain Information (FCI) to allow the official veterinarian and inspectors to gather enough information with sufficient time to define the risk of each batch, according to the agreed criteria, and to implement the appropriate post-mortem method and arrangements
3. A potential increase in the number of carcases in need of further handling before they are released to the chillers and the consequent resource implications, whether that be in terms of capital
Alterations to plant layout and staff resources to handle additional carcass dressing will need to be plant specific.
FSA145003 Final report ANNEX 5 v6 Page 24 of 25
Potential Obstacles Potential Adaptations
investment and alterations in the layout of abattoirs, or plant staff numbers and training.
4. The implementation of mechanisms to ensure that detection of conditions by visual inspection is maximised (e.g. some parts of carcases/offal may not be accessible to the visual inspection) and the consequent resource implications.
Additional mechanisms to ensure access and visibility to carcases and offal will need to be plant specific. Risk managers will need to consider if the resource implications are proportionate to the perceived risk and the potential gain. Examples include changes to the layout of the abattoir, or plant staff tasks, such as introducing rotating tools or mirrors to allow access to all parts of carcases/offal or the preparation of offal (opening of hearts) prior to inspection
5. The need to transfer additional meat quality responsibilities to the FBO to deal with all the aesthetic conditions in carcases (such as hair contamination) that no longer fall within the food safety authorities remit
There are no immediate solutions to these obstacles; they will be plant-specific. Food business operators will need revise their HACCP plans to address these issues
6. The potential for an increase in microbial contamination of carcases during the plant procedures to handle and deal with the above aesthetic conditions (after official post-mortem inspection).
7. A perceived, or actual, loss of data on animal health and welfare from animals slaughtered in the abattoir
Further work to identify the utility and benefits of the use of alternative data sources, such as plant own records of detection found in the abattoir (e.g. HACCP records), followed by the implementation of appropriate systems where relevant.
8. FSA personnel - perception of possible loss of their jobs as a consequence of new system
It is outwith the scope of Project FS145003 to suggest methods of change management and how to achieve behavioural change; however, training (and subsequent auditing) of all FSA personnel involved with the new system will be needed to ensure an adequate understanding of the concepts and responsibilities that are involved and so to maintain a high standard of service.
9. Decrease of the FSA MHI service quality due to different factors, such as the lack of experience with the new post-mortem inspection method, or the decrease of attention during post-mortem inspection due to the monotony of the task.
10. A perceived, or actual, decrease in the quality of the Official Veterinarian work, such as identification of high risk batches in need of a post-mortem inspection with inclusion of further incision of palpation, due to the lack of experience with the new system.
FSA145003 Final report ANNEX 5 v6 Page 25 of 25
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