Seroprevalence of Bovine Leukemia Virus (BLV) Infection in Pregnant Replacement Dairy Heifers in Saraburi Province, Thailand

Seroprevalence of bovine leukemia virus (BLV) infection was studied in replacement dairy heifers. Blood samples were collected from 80 pregnant heifers raised in 8 dairy farms in Saraburi province, the central part of Thailand and serum samples were tested for antibodies against BLV infection using commercially available ELISA test kits. The results revealed that 26 (32.5%) pregnant heifers were positive reactors, which was higher than seroprevalence of BLV in lactating dairy cows previously reported in Thailand. This study provided an evidence of a high seroprevalence of BLV in replacement heifers raised in areas of Saraburi province. It was crucial to the dairy farmers to be aware of this disease in replacement heifer rearing. Although serological test does not provide information of the infection at the early stage and is not sensitive enough to detect every infected animals, elimination of seropositive animals and prohibition of introduction of seropositive animals are sufficient to promote BLV-free herds in Thailand.