Journal of Dairy Science, Vol 75, Issue 8 2265-2271, Copyright
© 1992 by American Dairy Science Association
Estimation of genetic parameters for somatic cell score in Holsteins
Y. Da, M. Grossman, I. Misztal and G. R. Wiggans
Department of Animal Sciences, University of Illinois, Urbana
61801.
Genetic parameters of somatic cell scores for Holstein cows were
estimated using an animal model and REML for two data sets. Set 1,
with 13,017 records from 5278 cows, was used to obtain variance
components, heritability, and repeatability for two lactation
measures: the simple average and the weighted average of test day
data. Set 2, with 14,418 records from 4806 cows, was used to obtain
genetic correlations for the simple average between lactations 1 and
2, between lactations 1 and 3, and between lactations 2 and 3. Simple
and weighted average of test day somatic cell scores had the same
heritabilities (.12) and repeatabilities (.35). Phenotypic variances
were about 1.2, and herd-sire interaction variances were small
(.002). Genetic correlation for somatic cell score was about .55
between lactations 1 and 2 and between lactations 1 and 3 and .65
between lactations 2 and 3. Phenotypic correlation was .20 between
lactations 1 and 2, .16 between lactations 1 and 3, and .31 between
lactations 2 and 3.
