Comparison of natural transmission of bovine leukemia virus in Holstein cows of two genetic lines selected for high and average milk production.
One hundred and fifty lactating Holstein cows from 2 genetic lines selected for high and average milk production were used in the study. Sera from 6 annual herd tests were analyzed by agar-gel immunodiffusion test for antibodies to bovine leukemia virus. Odds of being seropositive were analyzed by use of stepwise and backward logistic regression procedures. Analysis within birth year revealed that estimated in odds increased by 0.19/year of age among cows of the high genetic line and by 0.43 among cows of the average genetic line. This was accompanied by a more important cohort effect among high producers than among average producers.
Detilleux
J C
JC
Department of Animal Science, Iowa State University, School of Veterinary Medicine, Ames 50011.
Freeman
A E
AE
Miller
L D
LD
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D001947:Breeding; D002417:Cattle; D015331:Cohort Studies; D016583:Enzootic Bovine Leukosis / Q000453:epidemiology / Q000235:genetics / Q000635:transmission*; D005260:Female; D005779:Immunodiffusion; D007774:Lactation / Q000235:genetics*; D001909:Leukemia Virus, Bovine / Q000276:immunology*; D015995:Prevalence; D012044:Regression Analysis
D000914:Antibodies, Viral