MAXIMUM LIKELIHOOD ESTIMATION OF GENETIC PARAMETERS IN CANADIENNE, BROWN SWISS, AND MILKING SHORTHORN

The application of maximum likelihood estimation of variance components to all lactation milk and fat records of three dairy breeds was accomplished with relative computational ease. Discussion of some of the practical problems of maximum likelihood estimation for the mixed model with sires and cows nested within sire is presented. Further study of a few of these problems is warranted. The estimated heritabilities for milk and fat yields were.27 for all three breeds, and repeatabilities were.50, except for Milking Shorthorn where repeatability estimates were.53 and.52 for milk and fat yield, respectively.