Farmers’ shock at scale of bovine virus

The government-funded project involved testing animals from 20 beef and dairy farms in Nidderdale for Bovine Viral Diarrhoea (BVD), which vets suspect is the undiagnosed reason for a lot of low-level problems.

More than half the animals tested, and 13 out of 20 of the herds, had been exposed to BVD, suggesting the virus had circulated on their farms at some point. Four herds had “persistently infected” carriers, meaning they had picked up the virus while their immune systems were still immature and would carry it for life.

RAFT Solutions, a subsidiary of Bishopton Vets of Ripon, ran the survey with the support of LANTRA LandSkills in Yorkshire, as part of the Rural Development Programme for England.

The vets’ report says: “BVD is widespread and can cause heavy financial losses.

“Acute infection may cause immuno-suppression with increased risk of other diseases, such as mastitis in adult cattle or pneumonia and scours in young stock.

“Effects on reproductive performance are also highly significant.

“Infection during mid pregnancy may cause abnormal development of eyes or brain and in early pregnancy may result in embryonic death.

“An immature immune system may fail to recognise BVD as foreign and a calf may then become ‘persistently infected’ (PI). These calves excrete huge amounts of virus but may appear to be normal.”

Testing involved blood sampling of young livestock and, for the dairy farms, a cross-check of samples from the milk tank, which can show the presence of any PI animals and lead to further investigation.

Two dairy herds and two beef had PI stock. Four dairy and six beef herds had animals which had been exposed to the virus. Only seven herds showed no evidence of BVD.

In at least two cases there were strong suspicions of infection from a neighbouring farm and one of the conclusions of the investigation was that boundary control was essential.

Jonathan Statham, of Bishopton Vets, said: “Control plans including a vaccination policy must include an annual booster for all breeding stock. Heifers must receive a primary course of two injections prior to service. Many herds fail to achieve correct timing of administration of vaccination and remain vulnerable to BVD challenge.

“Vaccination should be considered if cattle are likely to come into contact with animals from other holdings and all bought-in replacements and bulls must be screened before entering the herd.”

Scotland and Ireland both have national control programmes for BVD and the Nidderdale project was part of a drive to raise awareness in England and Wales.

Andrew Fisher, of Pateley Bridge, who breeds British Whites and sells some as beef through Weeton’s of Harrogate, was beginning to worry about picking up BVD at shows and volunteered to take part in the survey – which confirmed that his herd had been touched by the problem. He has now signed up for a full vaccination programme.

He said: “At £2 per vaccina-tion, it’s peanuts compared with the problems.”

Dairy farmer Mark Nicholson, of Ripon, has had his herd on a vaccination programme since 2006. But the survey revealed a gap in his system.

He said: “For three years we turned heifers out to grass in early stages of pregnancy with unvaccinated neighbouring stock. Unbeknown to us at the time, but as a result of this, we had two PI calves born in autumn 2008.

“BVD is something all cattle farmers have to start getting to grips with.”

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