Breeding Bulls and Bovine Leukemia Virus

By Barry Whitworth, DVM / Area Food/Animal Quality and Health Specialist for Eastern Oklahoma

In most beef enterprises, purchasing a breeding bull is a substantial investment. Most buyers insist the bull pass a Bovine Breeding Soundness Exam. This gives some assurance the bull is in good health and is fertile. However, most buyers do not routinely test bulls for reproductive or health diseases. Trichomoniasis, Bovine Viral Diarrhea Virus, and Bovine Leukemia Virus (BLV) are a few of the diseases that can have unwanted health consequences in a herd for years to come. A recent study evaluated BLV in bulls as possible source of transmission.¹

Bovine Leukemia Virus (BLV) is a retrovirus capable of causing cancer in cattle. The disease that is caused by the virus may be referred to as Enzootic Bovine Leukosis (EBL), malignant lymphoma, or lymphosarcoma. In the United States it is estimated 44 percent of dairy cows and 10 percent of beef cows are infected with the virus.2,3 Most cattle that are infected with the virus are asymptomatic or show no clinical signs of the disease. BLV is responsible for production losses due to increase veterinary cost, reproduction inefficiency, decreased milk production, and deaths.

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