Testing blood plasma from cattle in leukosos-free herds for antibodies against bovine leukemia virus (BLV)

As a prelude to the introduction of serological methods in the Danish leukosis eradication programme, an examination for antibody to Bovine Leukemia Virus (BLV) was carried out in 215 randomly selected leukosis-free herds in three areas where 3 routine haematological screening tests had bee made over a period of 6 years. A gel diffusion test was applied to plasma samples. Of 3319 animals screened, none were found to have detectable levels of antibody to BLV in their plasma. This would seem to indicate that false positive reactions are not a serious problem in connection with this test, and also that herds classified as leukosis-free after a series of haematological herd tests carried out within a period of some years, are in fact free from infection with Bovine Leukemia Virus.