Date of this Version
Records from 97,555 first daughters of 1,487 Holstein sires in artificial insemination were used to estimate components of variance and covariance of first lactation milk and fat production and stayability to 36, 48, 60, 72, and 84 mo of age. Henderson's Method 3 was used with a model including fixed herd-year- season and genetic group effects and random sire within group and residual effects. Heritabilities for milk and fat production and 36-, 48-, 60-, 72-, and 84-mo stayability were .31, .30, .02, .04, .05, .05, and .05. Genetic and phenotypic correlations between milk production and stayability ranged from .47 to .65 and from. 17 to .27. Adjusting components of variance of stayability to account for the correlation with milk reduced heritability of stayability by 35%. Genetic and phenotypic correlations between stayabilities to different ages ranged from .71 to 1.00 and from .18 to .73.