Components of Variance of Dairymen's Workability Traits Among Holstein Cows

Dairymen of an artificial insemination cooperative subjectively evaluated 5,601 of their cows in first lactation sired by 187 young Holstein bulls for temperament, milking speed, udder, leg and foot problems, and milk production. Exclusive categories were defined for each characteristic. Individual categories were separate traits, and components of variance and covariance were estimated for herd-year of measurement, sire of cow, and residual effects. Variance from sire of cow was less than 3% of the total for all traits so that heritabilities within herd-year were less than .12 for every trait. Variances and covariances were used in a multiple trait sire evaluation procedure to predict frequencies of future daughters for each category.