Journal of Dairy Science, Vol 78, Issue 4 939-946, Copyright ©
1995 by American Dairy Science Association
Variance of interaction effects of sire and herd for yield traits of
Holsteins in California, New York, and Pennsylvania with an animal model
G. Dimov, L. G. Albuquerque, J. F. Keown, L. D. Van Vleck and H. D.
Norman
Department of Animal Science, University of
Nebraska, Lincoln 68583-0908, USA.
An animal model with a REML algorithm was used to estimate variances of
additive genetic effects and interaction effects of sire and herd. Milk
and fat yields were analyzed for first, second, and third lactations
of Holsteins from California, New York, and Pennsylvania. Twenty
samples of data were used in the study: 10 from California, 4 from
New York, and 6 from Pennsylvania. Mean number of lactations per
sample was 36,820 from 18,189 cows in 156 herds. Mean fractions of
phenotypic variance of interaction effects of sire and herd for milk
and fat yields were .015 and .019 for first lactation and .019 and
.021 for all (up to three) lactations rather than the .14 used for
national genetic evaluations in the US. Mean heritability estimates
for milk and fat yields were .26 and .24 for first lactation and .21
and .21 for all lactations in California and .34 and .35 for first
lactations and .28 and .29 for all lactations in New York. Sums of
variances of permanent environmental and interaction effects of sire and
herd were similar to those used for national genetic evaluations in the
US. Analysis of another 10 samples from California and 10 samples
from New York showed only slightly different fractions of phenotypic
variance for milk yield for interaction effects of sire by herd, sire
by herd by year, and sire by herd by year by season: .023, .027, and
.037 for California and .023, .017, and .023 for New York,
respectively.
