Association between the level of antibodies in bulk tank milk and bovine respiratory syncytial virus exposure in the herd

Klem, T. B.; Tollersrud, T.; Østerås, O.; Stokstad, M.

This study shows that measurement of antibodies in BTM is a very slow changing tool to monitor BRSV in a herd. The antibody level in BTM will remain high for at least four years after a BRSV infection, even without reinfection. A positive BTM sample can be caused by only a few seropositive animals, and even a relatively strong increase in paired BTM test results does not necessarily indicate a new infection. This information is useful when BTM is used both in investigation of outbreaks and for surveillance or control purposes. BTM gives information on a large group of animals and are often readily available, but sampling of young animals will provide better and more updated information of the BRSV status of the herd.