This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Thurmond, M. C. Articles by Carter, R. L. Search for Related Content PubMed PubMed Citation Articles by Thurmond, M. C. Articles by Carter, R. L.

Cull Rates of Dairy Cattle with Antibodies to Bovine Leukemia Virus¹

Department of Medicine [M. C. T.], Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California (Davis), Tulare, California, 93274, and the Departments of Statistics [R. L. C.] and Preventive Medicine [C. B. M.], University of Florida, Gainesville, Florida 32601

The relationship of cull rate to age was investigated retrospectively in dairy cows with and without antibodies to bovine leukemia virus (BLV). Banked sera from eight annual herd tests on one 200-cow herd were tested for presence of BLV antibodies by agar-gel immunodiffusion using the M_r 51,000 glycoprotein antigen of BLV. Age-specific cull rates were computed for BLV-antibody-positive and antibody-negative cows yearly from 2 to 7 years of age. Cull rates, transformed by the Arc-sin square root, were analyzed by weighted regression. Transformed cull rates increased significantly as BLV-antibody-positive cows aged (one-tailed P = 0.023) but not as antibody-negative cows aged (one-tailed P = 0.59). A Mantel-Byar survival analysis showed significantly longer survival beyond 3.5 years of age among antibody-negative cows than among antibody-positive cows (P = 0.008).

¹ Supported in part by USDA Cooperative Agreement 58-519B-872 and with funds provided by the USDA under the Animal Health Act of 1977, Public Law 95-113.

² To whom requests for reprints should be addressed, at Department of Medicine, Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California, 18830 Road 112, Tulare, CA 93274.

³ Present address: Department of Preventive Medicine, University of Florida, Gainesville, FL 32601.

⁴ Present address: Department of Statistics, University of Florida, Gainesville, FL 32601.

Received 8/ 3/84. Revised 2/ 4/85. Accepted 2/ 6/85.