PRACTICES from Lincolnshire to Cornwall and Norfolk to Wales can expect a considerable upsurge of interest in the management of Johne’s disease. Not only did 350 farmers attend 14 meetings during March but 572 signed up for a 30cow herd screen.
Part of the programme is a sevenpage biosecurity risk assessment completed by the farmers and these are arriving by post, fully completed; the findings will be put through the MyHealthyHerd system and forwarded to the farmer and his vet for further action. The response from the farmers has exceeded expectation.
The Johne’s Disease Initiative testing has been funded by farmer subscriptions to Dairy Crest Direct, the independent farmer group that supplies milk to Dairy Crest. “Knowledge transfer” was supported by DairyCo, with training sessions for the seven veterinary surgeon presenters who took part.
Cow selection
Completion of many of the herd screens took place before the meetings. The farmers were advised to select older cows and under-performing cows, including those with high cell counts, barren cows, poor yielders and cows already targeted for culling.
Discussions took place between the farmer and his own vet about the selection but the aim was to include animals that offered the greatest chance of finding the disease. All veterinary practices within the areas were contacted by mail but not all responded.
This is not the end of the programme, just the start, so any practices that wish to become involved should contact Karen Lancaster (karen.lancaster@dairyco.org.uk).
Milk Buyers in general are considering taking up this initiative so more and more farmers can be expected to wish to participate.
Moving beyond the meetings, testing and assessments are “impact groups”. These are small groups of farmers that meet to discuss a particular topic. In this way farmers can continue to gather information and focus on their own herd situation, look for practical solutions and maintain a forward momentum, including on-going discussions with their vet.
What seems important is that the initiative is looking at ways of managing the disease with a “can do” approach, not a fire-and-brimstone allhell-let-loose culling sortie. This recognises that many of the cattle herds are experiencing culling due to bTB, which reduces enthusiasm for any further culling options.
Whole herd quarterly milk testing is considered to be the best option available. The 30-cow initial screen can give a false sense of security and because of the high prevalence of Johne’s disease in UK cows, repeated screening is advised.
Cows should be milk or blood tested close to drying-off. Positive cows are identified and treated as high risk. High risk cows need to be handled separately at calving to prevent transfer of infection to calves.
Forward planning
Although transfer is classically accepted as occurring within the first month of life, it is recognised that the first 24 hours are important. Forward planning of the calving facilities is essential. Calves from test positive animals are not kept as replacement breeding stock.
Vaccination increases immunity and reduces the clinical incidence but does not eliminate excretion of the bacteria. Vaccinated stock can cross react with the bTB test and the Johne’s surveillance test.
Infection transfer can occur within the uterus but it is infected colostrum and contamination by faeces on teats and within bedding that needs to be tightly controlled. Waste milk fed to calves can contain infection.
As raised cell count, lameness, displaced abomasum, downer cows and respiratory disease are recognised consequences of Johne’s disease, the likelihood of transfer of infection from cows that are being treated for other problems is high.
Infected cows produce less milk (4,000kg in a lifetime of production), are five times more likely to be lame, twice as likely to have a high cell count and record a 1.8 times increase in digestive and respiratory disease.
Risk assessment
Clinical cases are not a good indicator of the presence of Johne’s disease. For a buyer’s vet to ask a seller’s vet to indicate the incidence of clinical cases in a herd is not helpful. Most cows will be culled from the herd before clinical signs appear.
Herd prevalence and screening records are more appropriate but there is no such thing as a Johne’s-free status.
Carrying out the risk assessment analysis is an important tool to direct herd management and disease control. The buying-in of infected cattle is the recognised route for introduction of infection.
Farmers taking part in the initiative are being encouraged to question more thoroughly the health status of all sources of cattle. The increase in cattle movements, following culling for footand-mouth disease and the need to replace TB and BSE slaughtered animals, has allowed the disease to spread between herds.
Slurry from other farms and contaminated water from neighbours’ land need careful management. Whatever the source, slurry is best spread on arable land to remove the risk of infected pasture.
If slurry is spread on grassland, the recommendation is not to allow youngstock to graze the pasture for one year. Other means of pasture contamination need to be considered.
There is a balance between wildlife populations and levels of disease risk. More information would be helpful on the disease transfer risk from deer and rabbits and also the role of sheep.
Dairy Crest Direct has produced a one-page report of the programme to date as part of its newsletter to members. This may be of interest to clients of veterinary practices as a succinct summary of the actions and relevance of disease control.
Copies are available from Michael Masters (company secretary of Dairy Crest Direct): e-mail mmasters @edgarley.fsworld.co.uk or telephone 01458 835060.
Mr Masters is clearly pleased with the uptake and response from farmers and veterinary practices. The initiative has had the full support of the DCD board led by DCD director, Phil Allin, a Devon farmer, who has promoted it from the outset.
Options
Initial interest was raised by a presentation from Hannah Pearse of National Milk Laboratories on the options available for disease testing and the Herdwise scheme. The veterinary surgeons fronting the presentations were Peter Orpin, Andrew Cobner, Dick Sibley, Benno Veenstra, Peter Plate, Richard Pearson and Nich Roper.
Karen Lancaster and Elizabeth Berry from DairyCo attended the meetings and a local extension officer for each region will provide the ongoing support arrangements with the impact groups.
It is most encouraging that many sections of the industry are coming together to tackle a serious production disease where there is no available treatment and no recovery with time.
