| Popis: |
Three methods of sire evaluation were compared empirically—herdmate comparison, least squares, and maximum likelihood. Michigan Dairy Herd Improvement Association Holstein data representing 10,620 first lactation records and 1,003 herd-year groups were analyzed. Forty individual bulls representing three artificial insemination units were evaluated. The rank correlations among herdmate comparison and least squares estimates ranged from 0.94 to 0.97. The rank correlations between the maximum likelihood evaluations and those computed by least squares and herdmate comparisons were .99 and .97, respectively. The sampling errors of the maximum likelihood sire constants were about 1.5% smaller than those for least squares estimates. |
