Protect the herds that are not infected with Johne’s disease and implement control plans to break the cycle in herds that are infected. This is the approach recommended by Leicestershire vet and developer of the myhealthyherd disease management scheme Peter Orpin.
Peter Orpin, director myhealthyherd
and partner: Park Vet Group, Leicester
“Producers need to access the risk and carry out routine surveillance and combine this with a robust plan that all involved in the dairy herd are engaged in,” he told producer and veterinary delegates at Dairy UK’s industry Johne’s conference this month (October 10).
“Johne’s disease was a problem on farms in the 1940’s where management allowed infection to spread easily from cow to calf. In the two decades from 1970 it was more of an ‘exotic’ disease thanks to improved hygiene, less stock trading and a more static herd size. But in the past 15 years there’s been more stock movements as herds have expanded and restocked post FMD, group calving has been practised and producers have pooled colostrums and fed waste milk to heifer calves. These factors have all contributed to the spread of Johne’s disease.”
The challenge now on farms and among vets is to recognise the prevalence of the disease – estimated to affect at least 65% of herds to some extent – and to reduce the risk of infection and spread through a robust control plan. A high disease status for Johne’s needs the support of strong biosecurity, surveillance and control ‘pillars’.
“Risk drives this disease,” added Mr Orpin. “Each farm needs to look at protecting the herd against disease entry with biosecurity measures and also prevent spread with in the herd through biocontainment practices. This is how we will bring Johne’s under control – sticking our heads in the sand is not an option. We need to manage the risk to manage the disease. We’re not talking about eradication at this stage. Controlling the disease is the priority right now.”
The extent of testing for Johne’s depends on the aspirations of the producer. “Those selling stock will want surveillance measures in place that give 100% assurance of their Johne’s status and CHeCs accredited. This typically involves routine annual whole herd screening of adult stock or quarterly testing of the herd. Others can use 30-cow screening of targeted animals and base control plans on this – which may or may not require more extensive testing.
“We also have to be very aware that the sensitivity of Johne’s tests improves as the disease progresses and with the frequency of testing.”
Protecting the herd from Johne’s requires the possible sites of infection to be blocked and the cycle to be broken. Producers buying in cattle need to be particularly vigilant and ask the right questions. On farm, infected cows must not be allowed to contaminate calves through colostrum, milk or faeces.
“The control plan for any farm relies on the producer and vet knowing the risks, the prevalence and having a clear idea of their aspirations,” added Mr Orpin. “Through myhealthyherd we have developed a range of control strategies for producers and vets - there’s a strategy for all farms.
“We have also developed a module that itemises all areas of risk that can be scored to show up weaknesses in the control plan and reduce the risk of new infections. Robust and effective risk management is the only way the disease will be controlled.”
Regular reviews by trained vets are also a crucial part of the control plan. “Through myhealthyherd we can predict the prevalence of Johne’s once a herd is monitored through the service. If the predicted prevalence is going down then we can be fairly sure the control plan is working and that it will be successful in future.”
And it’s the ability now to be able to pick up high risk herds then predict and prevent the impact of the disease that will bring Johne’s under control. “This means measures can be put in place before an infected cow – that may not be picked up through surveillance for a few years – has spread the infection to her calf and others. There’s no need to wait for the disease before taking any action – herds that score ‘red’ for entry and ‘red’ for spread on the myhealthyherd system should be targeted for action irrespective of whether they have positive test results.”
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