29 August 1997

New measures to combat BVD

STRICTER controls on embryo transfer in dairy cattle to curb the spread of bovine viral diarrhoea virus (BVD) are being called for by the Institute of Animal Health (IAH), Compton, Berks.

IAH scientists believe that current controls imposed by the International Embryo Transfer Society are inadequate. ITES has attempted to curb the virus spreading through commercial ET by advocating the washing of embryos before transfer or freezing. But this procedure fails to remove traces of the virus collected from cows infected with BVD, says the IAH. Evidence comes from its MDC-funded study examining BVD in seven-day-old embryos.

Project leader Bryan Charleston says the research has also found that cattle immune to one strain of BVD are not necessarily fully protected against other strains.

"Importing the virus from other countries, therefore, is a particular concern because some countries, especially North America, have different strains of BVD."

The IAH has issued three recommendations to stem BVD risks:

&#8226 Virus negative cows should not come in contact with BVD three weeks before embryo collection

&#8226 Embryos should be stored after collection until tests have confirmed the donor did not become infected with BVD. Blood samples should, therefore, be taken before and after the ET programme.

&#8226 Farmers must avoid exposing donor cows to new strains of BVD three weeks prior to embryo collection.n