Bovine leukemia virus in Michigan beef bulls

Abstract

Bovine leukemia virus (BLV) is a contagious retrovirus of cattle. Little is known about the prevalence, risk factors, or potential health impacts of BLV in beef cattle. Most cattle remain asymptomatic, but 30 to 40% will develop persistent leukocytosis. Fewer than 5% of infected cattle develop malignant lymphosarcoma, which in the US, is the most common neoplastic disease of cattle discovered at slaughter. Recent studies have suggested that BLV prevalence has increased dramatically, and has a previously unappreciated economic impact on the cattle industry. The objectives of this study were to determine the crude and age-specific prevalence of BLV among beef bulls in Michigan, assess the possible impact of BLV infection on bull fertility, and identify the major risk factors for BLV transmission among beef bulls.