The Action Group on Johne’s has drawn up a list of six different strategies for Johne’s control on GB dairy farms. These strategies cover every GB dairy farm scenario. Discuss with your BCVA Accredited Johne’s Veterinary Advisor which control option is best suited to your herd.
Each individual farm needs to determine the most appropriate strategy for them by assessing factors such as:
- Current prevalence of Johne’s on the farm
- Biosecurity risk associated with the farm (eg buying in of stock)
- Biocontainment risk associated with the farm (eg risk of spread within the holding)
- Resources (capital and human)
- Aspiration of the farm (eg desire to eradicate Johne’s completely or simply contain the disease at manageable levels)
Take a look at each of our strategies and read our case studies taken from some of our farmers.
The SIX different control strategies and case studies are set out below:
1. Biosecurity Protect and Monitor
This option is suitable for herds which have completed appropriate screening tests and have no evidence of disease. A robust biosecurity protocol must be established to minimise the risk of bringing the disease in, this must address buying practice, slurry and grazing management. Surveillance testing is required to monitor the herd status and detect incursions of disease. The level of surveillance required will depend on farmer aspiration and the risk of introducing Johne's disease into the herd.
For example a farm which buys in multiple animals would require a higher level of surveillance than a truly closed herd. Also a herd wishing to pursue accreditation through the Cattle Health Certification Standards (CHeCS) (which may attract a premium when selling stock) would need to undertake whole herd testing as per the scheme requirements. It must be remembered that with minimal surveillance testing it may be possible to miss the arrival of the disease and allow it to gain a foothold within the herd before it is identified, especially if the herd has management strategies which would facilitate spread.
Read the Case Studies.
2. Improved Farm Management
This option relies on breaking the cycle of disease transmission from cow to calf through management changes implemented across all cows in the herd. These changes will concentrate on calving, colostrum and milk management. No individual cow testing is undertaken and so all cows must be treated as if they are infected and a risk. The important thing to bear in mind with this strategy is that these changes MUST be implemented across EVERY cow in the herd.
This option is best suited to smaller herds with low risk and low prevalence which are able to commit labour resource to the system. Without excellent compliance this strategy will not work, and as there is no testing, there is no way of monitoring the disease. A level of herd surveillance testing should be considered, at least to establish a starting point and then periodically to be able to assess the effectiveness of the control programme.
Read the Case Studies.
3. Improved Farm Management and Strategic Testing
This option uses strategic individual cow testing to identify those cows most at risk of spreading Johne's disease and implementing management changes to break the cycle of transmission for these cows only. This allows the management changes to be targeted at those cows which pose the highest risk whilst allowing normal management of the remainder of the herd. Testing is carried out to identify high risk cows at a time appropriate to reduce the risk of transmission through management changes.
There are three options which are described in more detail below. It should be noted that the more frequent the testing, the more sensitive the results.
Read the Case Studies.
4. Improved Farm Management Test and Cull
An addition to the Improved farm management & strategic testing option with immediate culling of test positives rather than retaining and managing them. This option would be suitable for low prevalence herds wanting to quickly remove infected animals. This option would not be suitable for high prevalence herds as it may be uneconomic to pursue and alternative strategies may be more suitable in the first instance. Read the Case Study.
5. Breed to Terminal Sire
No replacement animals are bred, all cows are served to a terminal beef sire and all offspring are fattened for slaughter. Replacements are sourced from herds with lower levels of Johne's disease. In effect they become a 'flying herd'. This strategy may be suitable for herds with a high risk and high prevalence with no wish to breed their own replacements or the ability/resource to manage the risks through improved farm management. This is not a way to remove Johne's disease and its effects from a farm.
Cows will still develop Johne's disease and will need to be removed from the herd, hopefully this number will reduce over time as they are replaced with uninfected bought in cows. It must also be remembered that on a farm with very high levels of Johne's disease transmission between adult animals is possible. It may still be prudent to undertake testing to help identify cows for removal. ALL calves produced in this system MUST be slaughtered for beef and NOT enter the suckler herd as breeding animals.
Read the Case Study.
6. Firebreak Vaccination
A vaccination is available for Johne's disease, however its efficacy is limited. In the dairy herd calves will frequently become infected within the first 24 hours of life meaning that they are already infected by the time they are vaccinated. The vaccine does not prevent infection, nor will it prevent an infected cow from shedding the bacteria and infecting others. It does extend the period before an infected cow shows clinical signs thus giving that cow a longer productive period before she succumbs to Johne's disease. Vaccination may be an option for high risk, high prevalence herds as a firebreak to 'buy some time' until another strategy can be adopted. Vaccination should not be undertaken without a clear exit strategy and a good understanding of the implications of vaccination. Once a herd is vaccinated it becomes very difficult to determine whether an animal is infected as the tests cannot differentiate between antibodies from vaccination and infection. This complicates the management of the disease. Vaccination must be undertaken under the advice and supervision of your vet.
Discuss with your vet which control option is best suited to your herd. The Johne's Action Group considers it very important that the choice of control strategy is determined through discussion with the farm vet.