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Livestock Science

Livestock Science 164 (2014) 149–153

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The impact of space allowance on productivity performanceand Salmonella spp. shedding in nursery pigs

Nenad Stojanac a,n, Ognjen Stevančević a, Aleksandar Potkonjak a, Božidar Savić b,Ivan Stančić a, Vuk Vračar a

a Department of Veterinary Medicine, Faculty of Agriculture, University of Novi Sad, Trg Dositelja Obradovića 8, 21000 Novi Sad,Republic of Serbiab Institute of Veterinary Medicine Belgrade, Serbia, Vojvode Toze 14, 11000 Belgrade, Serbia

a r t i c l e i n f o

Article history:Received 16 November 2013Received in revised form27 March 2014Accepted 29 March 2014

Keywords:PigletPiglet housingSalmonella spp.Space allowance

x.doi.org/10.1016/j.livsci.2014.03.02713/& 2014 Elsevier B.V. All rights reserved.

esponding author. Tel.: þ381 21 485 3515;81 21 635 0419.ail address: stojanac.n@gmail.com (N. Stojan

a b s t r a c t

The object of this study was to determine the effect of the area available per piglet, duringthe nurturing phase, on production performance and presence of Salmonella spp. Testingwas performed on two farrow-to-finish farms over a period of two years. The study wascarried out in three variants: 0.16 m2, 0.25 m2 and 0.32 m2 of floor space per piglet. Pooledfaeces samples, which were tested for the presence of Salmonella spp., were collectedthree times during the nurturing stage: 7, 21 and 35 days after weaning. The piglets whichhad the lowest spatial area available (0.16 m2) had average daily gain (ADG) significantlylower (Po0.05), and feed conversion ratio (FCR) higher than piglets with 0.25 m2 and0.32 m2 of floor space available. Morbidity and mortality were significantly higher inpiglets with 0.16 m2 of floor space available, compared to piglets housed on larger floorspaces, for both farms examined. The overall presence of Salmonella spp. was 6.2% (19/306). Out of 19 Salmonella-positive faecal samples, 15 were from piglets with 0.16 m2 offloor space available (78.9%). The results showed that holding piglets in an area smallerthan recommended has no economic justification and may imposes a higher risks ofinfection of piglets.

& 2014 Elsevier B.V. All rights reserved.

1. Introduction

In modern and intensive production of pigs there is aconstant need to increase productivity in both the reproduc-tive and capacitive senses. Determination of the floor areaneeded by each animal requires an allometric approach(Gonyou et al., 2006). Available floor area is directly corre-lated with piglet's body weight (A¼k�BW2/3), where Arepresents an area in m2, BW is body weight, and k is a

ac).

variable coefficient, with currently allowed values in the EUranging from 0.027 to 0.043, depending on the weight of thepig. The EU Scientific Veterinary Committee recommendsthat the minimum available area by piglet is calculated usingthe value of k¼0.047 (SVC, 1997), and the same is recom-mended by the EU Scientific Panel on Animal Health andWelfare, because this is the area which is required fortemperatures higher than 25 1C (AHAW, 2005).

With increasing pig housing density, the animals’ suscept-ibility to disease also increases. Recently, pig diseases havebecome endemic in many countries, and they escalate withthe advent of social stress of piglets (Sutherland et al., 2007),which is the result of increasing density of pig populations(Alarcon et al., 2011; Marco-Ramell et al., 2011). Producers of

N. Stojanac et al. / Livestock Science 164 (2014) 149–153150

pigs always have a goal to produce more animals with betterproduction performances, to be more competitive in themarket.

On the other hand, in the global market, food producedin the natural way is becoming more desirable, andconsequently, manufacturers' commitment to this type ofpig production is also gaining strength. In addition to this,food safety is a very important aspect. It is, therefore,imperative that the pigs are free from those pathogenswhich are potential causes of human foodborne disease.Pigs infected with Salmonella spp. are an important sourceof Salmonella spp. infection in humans. Piglets with con-firmed presence of Salmonella spp. represent a high risk forcontamination of meat, and therefore for safety and healthof humans (Beloeil et al., 2004; De Busser et al., 2013).By reducing Salmonella spp. in the intestinal tract ofpiglets, the pressure of contamination of pork is reduced.Funk et al. (2001) in their research found that withincreasing density of population of fattened pigs, thepresence of Salmonella spp. also increased.

The aim of this study was to investigate the effect of theavailable floor area per piglet during the nurturing phaseon the productive performance (average daily gain (ADG),feed conversion ratio (FCR), morbidity and mortality ofpiglets) and the presence of Salmonella spp. in piglets.

2. Material and methods

The testing was performed on two farrow-to-finishfarms (A and B) with capacities of 1200 and 2000 sows,respectively, over a period of 2 years (2011–2013). Bothfarms had the technology based on weekly management.Groups for weekly farrowing were comprised of 60 (farmA) and 110 (farm B) sows. Lactation lasted for 28 (73)days, after which the piglets were weaned. The averageweight of piglets at weaning was 7.1 (70.5) kg. Pigletsremained in the nursery for 42 days (22–24 kg), afterwhich they were moved to fattening facilities. Piglets hadad libitum access to feed and water on both farms. The allin/all out principle was used on the farms, and after thecompletion of each phase, the facilities were cleaned,washed and disinfected.

Both farms used cages for housing piglets in nurseries.The floors were in the form of a grid covering 2/3 of thearea, while 1/3 was the heating plate, which was used whenthe ambient temperature was below 20 1C. Farm A hadnurturing boxes with floor areas of 2.8 m2 (200�140 mm),and one pen had 34 boxes. Farm A had 7 pens for breedingpiglets. Farm B had boxes with floor areas of 1.65 m2

(157�105 mm) and one pen had 22 boxes. Farm B had 25pens for breeding piglets.

Table 1Number and size of groups studied for the three space allowances.

Number pigletsin group

Number groups Box size (

Farm A 5007120 20 2.8Farm B 1000750 14 1.65

2.1. Study design

On farm A, 20 groups of piglets were monitored duringthe study period. Each group had 5007120 piglets. Thestudy was done in three variants in each group: the boxeswere filled with 17 piglets (0.16 m2 per piglet), 11 piglets(0.25 m2 per piglet) or 9 piglets (0.32 m2 per piglet).In total, 9900 piglets are examined and, within each group,the piglets were kept with three rearing systems that areexamined in this study (Table 1).

On farm B, 14 groups of piglets were monitored duringthe study period. Each group had 1000750 piglets. At thestart of the study, each group had box was filled with 10piglets (0.16 m2 per piglet); 7 piglets (0.25 m2 per piglet);or 5 piglets (0.32 m2 per piglet. In total, 13,800 piglets areexamined and, within each group, the piglets were keptwith three rearing systems that are examined in this study(Table 1).

2.2. Sample collection and laboratory analysis

Pooled faeces samples, examined for the presence ofSalmonella spp., were collected three times during thenurturing phase: 7, 21 and 35 days after weaning. On farmA, three pooled faecal samples were taken from each of the20 groups of piglets during each visit. The first faecalsample was taken from the two boxes where piglets werereared in 0.16 m2 of the space allowance per piglet; thesecond, from the three boxes where piglets were reared in0.25 m2 of the space allowance per piglet; and the third,from the four boxes where piglets were reared in 0.32 m2

of the space allowance per piglet. So, each sample con-tained faeces of 35 piglets. In total, 180 samples wereanalysed from farm A. On farm B, three pooled faecalsamples were taken from each of the 14 groups of pigletsduring each visit. The first faecal sample was taken fromthe seven boxes where piglets were reared in 0.16 m2 ofthe space allowance per piglet; the second, from the tenboxes where piglets were reared in 0.25 m2 of the spaceallowance per piglet; and the third, from the fourteenboxes where piglets were reared in 0.32 m2 of the spaceallowance per piglet. So, each sample contained faeces of 70piglets. In total, 126 samples were analysed from farm B.Factors that were evaluated in the process of taking ofpooled faeces samples were: presence of diarrhoea in thebox, sick animals in the box and slow growth of piglets.

The pooled faecal sample was obtained from the samenumber of piglets within a farm for all 3 stocking densities.

Faecal samples were collected into sterile containers andtransported on ice packs to the laboratory within 2–4 h andcultured immediately. ISO 6579:2002 method was followed.Briefly, each sample was incubated in buffered peptone

m2) Piglets per box

0.16 m2 /pig 0.25 m2 /pig 0.32 m2 /pig

17 11 910 7 5

N. Stojanac et al. / Livestock Science 164 (2014) 149–153 151

water (BPW; Oxoid) for 18 h at 37 1C (pre-enrichment step).Subsequently, 1 ml was transferred to 10 ml of MullerKauffmann tetrathionate-novobiocin broth (MKTTn, Oxoid,Hampshire, England, UK) and 0.1 ml was transferred to 10 mlof Rappaport Vassiliadis Broth with soya (RVS, Oxoid) andincubated at 37 1C and 41.5 1C, respectively, for 24 h (enrich-ment step). Then, both xylose lysine deoxycholate agar(XLDA, Oxoid) and Salmonella Chromogenic agar (SHA,Oxoid) plates were inoculated from RVS broth. Also, bothbrilliant green agar (BGA, Oxoid) and XLDA plates wereinoculated from MKTTn broth. All the plates were incubatedat 37 1C for 24 h. Suspect colonies (with black centre and/orpink from XLDA, pink from BGA or magenta from SHA) werepurified on a nutrient agar and confirmed biochemicallyusing API 20E kits (BioMérieux, France) and serologicallyusing poly O antiserum (Pro-Lab Diagnostics, Canada).

2.3. Production data and statistical analyses

The following indicators of production performancewere examined: average daily gain (ADG), feed conversionratio (FCR), morbidity (culls) and mortality of piglets. ADGrepresents the difference between the total weights ofpiglets at the moments of entrance and exit from nursery,divided by the average number of days spent in thenursery. FCR is the total amount of feed consumed, dividedby the weight gain. Measurements of ADG and FCR wereperformed for each box individually. Culls and mortality ofpiglets show the percentage of culls and dead piglets andwere calculated for each individual group.

Table 2Salmonella spp. shedding and production performance results for piglets housed

Farm A

Space allowanceand k-value

Number of piglets Number positiveSalmonella spp./20 pooled f

m²/piglet k – 23 kg 7 days 21 days

0.16 0.019 3700 2 00.25 0.030 3200 0 10.32 0.039 3000 1 0

a P40.05.b Po0.05.

Table 3Salmonella spp. shedding and production performance results for piglets housed

Farm B

Space allowanceand k-value

Number of piglets Number positiveSalmonella spp./14 pooled fa

m²/piglet k – 23 kg 7 days 21 days

0.16 0.019 5300 2 30.25 0.030 4500 0 00.32 0.039 4000 1 0

a P40.05.b Po0.05.

Data were entered into an Excel spreadsheet (MicrosoftExcel 2010) and imported into Stata (Stata 8 Intercooledfor Windows 9x) in which data were analysed. Descriptiveanalysis was done in MiniTab version 14 (MiniTabR14b)and Excel (Microsoft Excel 2010).

The experimental unit used to compare group sizes wasthe box. The differences among treatments were statisti-cally analysed with a one-way ANOVA test in a completelyrandomized design using Statistical Packages for the SocialSciences (SPSS, 2001), for ADG and FCR. The significantdifferences among means were compared using Post HocTest. Mortality and culls were analysed in a logisticregression using the procedure GENMOD in SAS (chi-squared (χ2) values were generated as the test statistic)and the results are expressed in percentages, while theresults of Salmonella spp. occurrence in faeces of pigletswere analysed by Kruskal–Wallis non-parametric test.Po0.05 was set as the limit of significance.

3. Results

3.1. Production performance

Production results are presented in Tables 2 and 3, foreach area capacity of both studied farms. On both studiedfarms, piglets had the lowest ADG and the highest FCRwhen they had 0.16 m2/piglet of available space. Pigletshoused with more available space (0.25 or 0.32 m2/piglet)had significantly higher (Po0.05) ADG and FCR. Therewere no significant differences (P40.05) between the

on farm A.

aecal samplesADG FCR Culls (%) Mortality (%)

35 days

4 228b 1.95b 292 (7.9) 181 (4.9)0 390a 1.86a 93 (2.9) 96 (3.0)0 395a 1.87a 86 (2.7) 93 (3.1)

on farm B.

ecal samplesADG FCR Culls (%) Mortality (%)

35 days

4 285b 1.98b 445 (8.4) 323 (6.1)1 380a 1.88a 139 (3.1) 153 (3.4)0 410a 1.82a 60 (1.5) 124 (3.1)

N. Stojanac et al. / Livestock Science 164 (2014) 149–153152

production results of piglets kept in areas with 0.25 and0.32 m2/piglet.

The number of culls and piglet deaths on both farmswas more than 2.5 times higher for piglets housed withonly 0.16 m2/piglet of available floor space, than for pigletswith 0.25 or 0.32 m2/piglet. On farm A, no significantdifference was observed (P40.05) in the number of cullsand deaths when piglets were housed with floor areas of0.25 and 0.32 m2/piglet, while on farm B, significantdifferences were observed (Po0.05) in the number ofculls and deaths, depending on the availability of floor areaper piglet (0.25 and 0.32 m2).

3.2. Faecal Salmonella spp. shedding

The presence of Salmonella spp. in piglets in nurseries ontwo farms studied with different area capacities is shown inTables 2 and 3. Overall, Salmonella spp. was isolated from6.2% (19/306) of pooled faeces samples from the studiedfarms. The greatest number of Salmonella-positive faecalsamples (8/19), was found on day 35 in piglets with theleast available floor area, on farm A (4) and farm B (4).

The results (Po0.05) indicate a relation between theavailable floor area per piglet and the presence of Salmo-nella spp. in piglet faeces. For both farms studied, each hadonly two positive case of Salmonella spp. in piglet faeceswhen the animal were housed on 0.25 or 0.32 m2/ piglet ofavailable floor space.

4. Discussion

The impact of the available area per fattened pig on pigproduction performance has been the research subject ofmany authors for many years (Petherick, 1983; Hurnik andLewis, 1991; Gonyou et al., 2006; Anil et al., 2007; Jensenet al., 2012) while data related to piglets in nurseries arequite scarce (Brumm et al., 2001; Smith et al., 2004). Onboth investigated farms, significantly lower productionresults, the lowest ADG, the highest FCR, and the highestculling rates and mortality, were identified in piglets with0.16 m2 of available space (Brumm et al., 2001), or calcu-lated allometrically, coefficient k �0.019 at the end of thenurturing. The minimum value of the coefficient k is 0.030,which other authors have cited as the minimum areaavailable per piglet (Gonyou and Stricklin, 1998, Wolteret al., 2000; Averos et al., 2010), suggesting that the area of0.16 m2 per piglet is adequate until 12.2 kg of body weight.On farm A, there was no difference in production results inpiglets kept within the available areas of 0.25 m2 and0.32 m2, while on farm B, there was difference in produc-tion results. This suggests that the production performanceimproves linearly with the increase of the surface area to acertain level, when these indicators reach their plateau(Gonyou et al., 2006).

In the current study, the highest presence of Salmonellaspp. was found in piglets with an available floor area of0.16 m2, i.e. 15 out of total 19 positive faecal sampleson both farm. This could be related to the larger number ofcull piglets also found in the higher density housing,although this relationship was not an aim of the currentstudy. Similar results were obtained by Morrow et al. (2002)

who reported that the presence of Salmonella spp. in pigletsdecreased with decrease of piglet population density.Increasing the population density increases the stress amongpiglets and they become more susceptible to endemicdiseases (Maes et al., 2001), which increases the risk shed-ding of Salmonella spp. (Funk et al., 2001). In the currentstudy, although there are limitations in interpretation of theresults, due to the small number of Salmonella-positiveanimals, our data indicate that increasing the area from0.25 m2 to 0.32 m2 per piglet did not lead to changes inSalmonella spp. shedding during the stage of nurturing. Funket al. (2007) in their studies related to fattened pigs, came upwith the same findings. Data on the presence of Salmonellaspp. in weaned piglets in this study represents just anintroduction to further research works based on the relation-ship of space allowance and Salmonella spp. in pigs.

5. Conclusions

Based on the results obtained in this study, it was foundthat breeding pigs below the recommended levels of areacapacity, leads to problems in piglets in nurseries, bothregarding production results, and regarding the safety ofpig meat for human nutrition.

Conflict of interest statement

The authors confirm that there are no known conflictsof interest associated with this publication and there hasbeen no significant financial support for this work thatcould have influenced its outcome.

Acknowledgement

This research was financially supported by the Ministryof Education, Science and Technological Development ofthe Republic of Serbia, Project no. TR31034.

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