JOHNES DISEASE PROJECT – 1ST YEAR RESULTS

Piers Pepperell & Alastair Caygill

What is it?• It’s a contagious bacterial disease of the bovine

intestine

• Slow growing bacteria that usually takes around 3-7 years to start causing problems

• Causes a slow thickening of the intestinal wall => reduced absorption => less nutrient uptake

• Causes reduced immunity to other conditions, reduced growth rates and increased culling rates

• Eventually ends as a terminal scour

• No treatment and no recovery

Reduces Lifetime performance• Cows give >2000kgs less

milk in a lifetime causing decreased calf growth rates

• 5 X more likely to be lame

• 2 X more likely to have mastitis

• 2 X more likely to have digestive or respiratory disease

• Causes financial loss by

1. Loss of carcass value of the dam

2. Decreased calf growth rates

3. Loss of premium from high health status of pedigree herds

Usually subclinical disease

• Many farms may never have seen a case because infected animals are culled for poor performance or fertility before they start to show symptoms

• For this reason if you have a clinical case, there may well be several more subclinical cows in your herd (some estimates are 10-20 subclinical cases for every clinical case)

Farms which had seen a case previous to the start of the project

Beef farms

Yes

No

Dairy farm

Yes

No

How is it spread?

Colostrum and milk 10-40 % in uteroinfection depending on level of infection

Faeces contaminating calves/ udders

Carriers shed intermittently in times of stress, shedding more and more as the disease advances

Main risk areas

• Contaminated calving areas – dung gets onto teats of non infected cow and is consumed by calf

• Cross suckling

• Feeding colostrum from another cow

• Hygiene usually better at pasture so housing is main area of spread

Other sources of infection

• Bought in Cows, Bulls and replacements

• Standing water sources – small lakes, ponds

• Slurry from other farms

• Sheep/Goats

• Rabbits?

Susceptibility decreases with age• When a calf is born it has a

large number of areas in it’s gut called Peyers Patches. Their job is to allow antibodies to be absorbed into the blood from the colostrum

• These shrink over time until they have gone by around 10mths of age

• It is through these that the Johnes enters the calf though colostrum, milk or dung consumed by the calf

• 80% of Johnes infections occur in the 1st month of life

Main spread area

• It is a shit into mouth disease. A carrier will shit onto the bedding, onto feed areas and even directly onto calves.

• A “super shedder” can discharge enough bacteria in 24 hours to infect 50000 calves

How can we test for it?• The closer the animal comes to developing

symptoms, the more sensitive the tests become. This means testing is ineffective under 2 years of age.

• Test the dung. This is the best test but quite expensive

• Blood test. This will pick up around 50% of infected cows. Best to do it as close to calving period as possible as increased stress increases the chance of picking it up

• Better to think of negative cows as “low risk of spread” cows

• If there is any risk the animal might be a carrier e.g. born to a positive mother, they should be treated as high risk until proven otherwise

Which animals to test?

• Regular quarterly whole herd samples Most reliable but very expensive

• Regular whole herd annual sample fairly reliable, more affordable and helps management decisions

• Whole herd individual sample useful but can give a false sense of security if not done regularly

• 30 cow screen okay start but may well miss some positives

• Individual/cull cows least reliable, very random

What we found in our 1st year

Beef farms

Positive animals found

No positive animals found

Dairy farms

Positive animals found

No positive animals found

Numbers on each farm

0

2

4

6

8

10

12

14

16

B D

Testing positive

Testing positive

• Positives were rebled a month later• Double positives were then dung tested

if requested• Several blood positives have been dung

negative. These are treated as medium or high risk depending on the farm history

• However we have now done the second year testing on 6 beef herds. Only 1 of them had positives last year and this year 5 out of the 6 have had positives!

What can you do to prevent Johnesdisease becoming a problem

• Nothing – risky

• Test a few – might give you a false sense of security

• Test whole herd and cull – this has been shown to only reduce the disease level very slowly

• Test, cull and make changes to stop the spread – shown to be the most effective

How to reduce spread of Johnes in infected herd– low level

• Clean calving areas-well bedded

• Calve cows outside• Test all animal prior to

calving and remove test positive and clinical cows early

• Only feed colostrumtaken from a young negative cow

Additional changes to reduce the spread of Johnes in medium to high infected herd

• Bleed everything prior to calving period.

• Separate infected and non infected cows into two groups if prevalence is high

• Source replacements from low prevalence herds or low prevalence groups

• Ensure the last calf from test positive animals are not kept as replacement breeding stock

Environmental controls

• Keep cows and their environment clean and free from faecal contamination, especially during calving period and first 6months of calves’ lives

• Prevent faecal contamination of feed and water supplies.

• Keep feed and water troughs clean

• Provide mains water and fence off other water sources

Environmental controls

• Spread dung or slurry on arable land, OR

• Do not graze youngstockfor at least 1 year on ground that has had dung or slurry spread on it

• Avoid co-grazing youngstock with other livestock that can be infected with Johnes

• Control rabbits

Any Questions?