Bovine TB – do you have a plan? (Nov/Dec 2021)

Vet and technical director of the TB Advisory Service Sarah Tomlinson shares the lowdown on controlling the disease and how to access free visits and invaluable advice.


TEXT SIMON WITHERS


Do you include bTB in your herd health plans? If not, Kingshay’s vet Sarah Tomlinson says you should. “Producers should take the view that bTB is just another infectious disease that they can, to some extent, take steps to control,” she says.


The TB Advisory Service (TBAS), which sets out to help producer take back some control when it comes to this devastating disease, has been running since 2017. “Many have taken advantage of the help on offer, yet some producers have not yet been able to access the service. But TBAS has secured more funding and is now able to offer advice and free visits to all producers across England,” says Ms Tomlinson.

Strict biosecurity: bTB bacteria can survive in slurry for six months


Although the service set out to deal with bTB just like any infectious disease, producers have no control around what they can and can’t do with their business when they are ‘shut down’ with it. “Breakdowns are not just catastrophic when it comes to dairy business finances, they also have a devastating impact on herd genetics, other health and welfare issues, and the mental health of producers and dairy staff. But there are things producers can do to help reduce the risk of bTB in their herd.”


Risk areas


She says there are five key risk areas that can be managed in a bid to reduce the risk of bTB infection. The first, and one of the most obvious, is taking steps to reduce contact between badgers and cattle.


“I always urge producers to get to know their badgers,” says Ms Tomlinson. “Use maps to mark established runs, setts and latrines. And do this regularly throughout the year because badger behaviour changes with the seasons.


“You can’t stop a heifer grazing where a badger may have urinated, but you can reduce access to setts. Even avoiding grazing young stock in fields at times when setts are particularly active, perhaps due to a maize crop close by, will reduce risk.”


Contamination of feed and water is another area producers can address. “Bovine TB bacteria survive for up to 60 days in water, so by reducing badger access, either raising troughs to one meter in height or simply emptying them when not in use, will eliminate or reduce the risk of bTB being transmitted. Protecting feed stores, such as maize silage, is possible with simple and cost-effective methods such as electric fencing. Wire running at 10cm, 15cm, 20cm and 30cm above ground level will prevent badger access,” says Ms Tomlinson.


Managing risk


Understanding the results of the skin test is key to managing risk. “As we have discovered during the COVID-19 pandemic, no test is perfect. With bTB, however, we do have a specific test. And we know a reactor testing positive is 99.98% likely to be infected with bTB and is infectious to other cattle, yet when slaughtered it may not have advanced enough disease to show lesions at slaughter. We need this level of certainty as the consequences of incorrectly identifying reactors are so devastating to a farm. Unfortunately the skin test has only moderate sensitivity, this is a measure of how many infected animals we identify. The skin test, when carried out correctly, is, at best, 80% sensitive. But, in practice, this means one in five infected animals is missed. This is important to consider when assessing the risk of buying in infected stock. The longer a herd has been tested and found to be bTB-free for, the more the most recent test can be trusted. The herd is more likely to be genuinely bTB free.


Testing tools: bTB skin test can be up to 80% sensitive


“From your own herd’s point of view, making a plan as to what risk you are prepared to take is important. Do you choose never to bring cattle onto your holding or to only buy from herds with the same number of bTB-free years as your herd? Each business is different, so you need to discuss with your vet what is appropriate for you.”


“There are other more sensitive bTB tests available, which can be used with permission from the Government’s Animal and Plant Health Agency. “These reduce the risk of infected animals being missed, and could have a use for pre- or post-movement testing.”


Neighbouring livestock is another risk factor producers should be aware of – and take steps to mitigate. “Ensuring no nose-to-nose contact can help. A wide and/or tall hedge helps here, or erecting a permanent or temporary fence three metres from the boundary. Some producers simply avoid putting cattle in a field if neighbour’s stock is grazing next to it.” Any shared equipment, whether it is a muck or slurry-spreading machinery, or transport visiting multiple units, can be a risk for most infectious diseases. Bovine TB bacteria can survive in slurry for six months, and insisting all farm visitors are visibly clean should be a standard requirement. “If you think slurry presents a bTB risk on your unit, think about using more precision-spreading techniques such as injectors or trailing shoe. Spreading onto arable land or silage leys, rather than grazing, will also reduce the bTB risk.”


Reduce stress


TBAS advisers are also on hand to discuss bTB test-failure plans. “No one likes to think the worst will happen, but producers say the support does help reduce stress and anxiety on testing days,” says Ms Tomlinson. “Identifying parts of the business that would be affected by movement restrictions – both off and on farm – helps producers plan what they can do in the short-, medium- and long-term if required.


“Producers who would typically sell young stock direct to a buyer could find out if they’d still take them if they were bTB restricted, with some notice. There are options, such as approved finishing units or orange markets, but would they take your age and breed of cattle, and what price are they willing to pay? Ask the questions and plan. Find out if you’d be better off keeping stock on farm or selling. Could you apply for an isolation unit?


“Think about your options, plan for the worst. Again, it’s about taking back some control. Producers feel more in control when they’re taking steps to prevent bTB from infecting their herd and, if they are still unlucky, they know they’ve done all they can and they also have a plan in place to manage and minimise the impact of being ‘shut down’.”


Producers can view the bTB history of other herds and units at: www.ibtb.co.uk. To book your free visit please contact TBAS on 01306 779410 or visit www.tbas.org.uk.

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