Bovine viral diarrhoea (BVD) is one of the biggest infectious disease challenges facing the cattle industry.
BVD has been estimated to cost the industry arount £40 million per year, which equates to £46.50 per cow, mainly attributed to fertility losses. However these estimates are likely to undervalue the losses through immunosuppression and secondary infections.
BVD is high on the UK agricultural sectors agenda and its control is supported by the Animal Health and Welfare Pathway and the NOAH vaccination guidelines. National eradication schemes have already proved to be working in Scotland (prevalence reduced to 10%) and Northern Ireland (prevalence reduced to 0.3%). And there are currently voluntary schemes in England and Wales.
Control revolves primarily around preventing the birth of persistently infected (PI) calves, which are a result of the dam getting infected with BVD in the first 120 days of pregnancy. A PI calf remains infected for life and continually sheds BVD virus, acting as a constant infection source for other animals.
Key points for a BVD control strategy:
1. Vaccination of all adult female breeding stock and heifer prior to first service to protect them from BVD infection during pregnancy.
2. Testing (e.g through tag and test schemes or youngstock blood screens or surveillance of bulk milk tank quarterly), identification and removal of PI animals from herds.
3. Maintaining a closed herd where possible. If not possible purchase from accredited BVD free herds. Quarantine and test all incoming stock and align them to your farms vaccination protocol.
4. Beware of buying in in calf animals. You can screen the dam for BVD but cannot be sure of the status of the calf until it is born, we recommend tagging and testing to ascertain the calves status as soon as possible.
Towcester Farm Vets has been proactive in encouraging its clients to test for BVD, as veterinary surgeon Nikki Moore explains: “We started offering to test for BVD at the same time as we did TB tests and had a good uptake.
Results were sometimes surprising, with some farms which we did not expect to have a problem testing positive and we also recognised the importance of testing annually, as a herd’s status did not necessarily stay the same.
Of the 90 herds we have tested over a five-year period, 17 have had a positive result and we have removed at least 30 PIs. We encourage vaccination of breeding cattle in addition to testing to provide a safety net to back up biosecurity measures.”