Enzootic bovine leukosis caused by the bovine leukemia virus (BLV) results in substantial damage to the livestock industry; however, we lack an effective cure or
vaccine.
BoLA-DRB3 polymorphism in BLV-infected cattle is associated with the proviral load (PVL), infectivity in the blood, development of
lymphoma, and in utero
infection of calves. Additionally, it is related to the PVL, infectivity, and anti-BLV antibody levels in milk. However, the effects of the
BoLA-DRB3 allele and
BLV infection on dairy cattle productivity remain poorly understood. Therefore, we investigated the effect of
BLV infection and
BoLA-DRB3 allele polymorphism on dairy cattle productivity in 147 Holstein dams raised on Japanese dairy farms. Our findings suggested that
BLV infection significantly increased milk yield. Furthermore, the
BoLA-DRB3 allele alone, and the combined effect of
BLV infection and the
BoLA-DRB3 allele had no effect. These results indicate that on-farm breeding and selection of resistant cattle, or the preferential elimination of susceptible cattle, does not affect dairy cattle productivity. Additionally,
BLV infection is more likely to affect dairy cattle productivity than
BoLA-DRB3 polymorphism.