Journal of Dairy Science, Vol 79, Issue 5 895-899, Copyright ©
1996 by American Dairy Science Association
Relationship of bovine leukocyte adhesion deficiency with genetic merit for
performance traits
R. L. Powell, H. D. Norman and C. M. Cowan
Animal Improvement Programs Laboratory, Agricultural Research Service,
USDA, Beltsville, MD 20705-2350, USA.
Examination of the existence of pleiotropy or linkage of bovine
leukocyte adhesion deficiency with other traits and of the impact of
removal of the recessive, undesirable allele on genetic progress for
those traits has been limited. Frequency of carriers among 6400
Holstein bulls tested was 8.2%; however, reporting was incomplete,
and, therefore, the estimate of carrier frequency was biased
downward. For AI-sampled bulls, carrier frequency reached a high of
23% for bulls sampled during 1989 but declined to 0% since then
because of DNA testing and culling. Association of the allele with
yield, productive life, and somatic cell score was examined with a
model in which the daughter yield deviation minus the mean of parent
evaluations was explained by carrier status. A significant negative
relationship was found with protein yield when effect of sires was
ignored; all associations were unfavorable. Linkage was examined by
applying the model for each of four sire families; only protein yield
for one sire was significantly and negatively related to the
recessive allele. Carrier bulls currently are labeled, and some
continue to be used actively in AI because of superiority for other
traits. Consequential pleiotropy of the allele or linkage of the
locus with the traits studied is unlikely. Genetic progress for these
performance traits will not be impeded by failure to sample carrier
bulls.
