johnes disease beef farm walk presentation
TRANSCRIPT
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JOHNES DISEASE PROJECT – 1ST YEAR RESULTS
Piers Pepperell & Alastair Caygill
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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
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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
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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)
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Farms which had seen a case previous to the start of the project
Beef farms
Yes
No
Dairy farm
Yes
No
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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
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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
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Other sources of infection
• Bought in Cows, Bulls and replacements
• Standing water sources – small lakes, ponds
• Slurry from other farms
• Sheep/Goats
• Rabbits?
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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
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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
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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
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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
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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
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Numbers on each farm
0
2
4
6
8
10
12
14
16
B D
Testing positive
Testing positive
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• 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!
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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
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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
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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
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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
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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
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Any Questions?