BOVINE LEUKOSIS

Bovine leukosis virus (BLV) is a cancerous condition of tissues, in wh ich lymph nodes and lymphocytes are affected. Infected cattle may be i dentified by testing blood sera for BLV antibodies using the agar gel immunodiffusion test. Most dairy farms have infected animals, but the condition is not considered important because less than 1% of infected cattle show clinical signs. Many of these cows, however, are culled b ecause of poor mill production or poor reproductive performance. This article discusses the diagnosis and transmission of BLV as well as its prevalence in U.S. dairies. Procedures for reducing and/or eliminatin g BLV are also discussed, including identifying BLV-infected animals t hrough regular blood testing, establishing practices and procedures to prevent the transfer of blood or other fluids from BLV-positive to BL V-negative animals, and isolating infected animals from noninfected an imals. Results obtained at the Kansas State University Dairy Teaching and Research Center demonstrate that feeding newborn and young calves colostrum and whole milk only from BLV-negative cows is an effective m ethod of reducing the incidence of BLV in future generations.