Sire Evaluation for Conformation of Jersey Cows

Abstract

A procedure for sire evaluation was developed for Jersey type data; the model contained fixed effects for herd-year and genetic group and random effects for sires, herds-by-sires, and cows.In initial calculations artificial insemination and natural service bulls were grouped separately by year of birth with little evidence of genetic trend for final score. These evaluations then were used for pedigree indexes based on sire and maternal grandsire. Bulls of similar pedigree index for each trait were grouped for new evaluations. The correlation between pedigree index and evaluation for final score on 726 bulls with type information on sire and maternal grandsire and 10 or more classified daughters was .64. The correlation for 533 bulls with evaluation on sires only was .58. The regressions of evaluations for final score on pedigree indexes were .73±.03 and .77±.05. Predicted Difference milk had correlations of .18, .13, .55, .13, and −.04 with evaluations for final score, general appearance, dairy character, body capacity, and mammary system. Other correlations ranged from −.09 for back, rump, and tail to .20 for breed character. Correlations between these evaluations and previous estimates of genetic merit, daughter averages of latest score, were .63, .61, .54, .48, and .69 for final score, general appearance, dairy character, body capacity, and mammary system. Similar correlations for other traits ranged from .47 for breed character to .76 for stature. An index combined estimated transmitting ability for milk, fat, and final score. Bulls were ranked by indexes; different weights were used for production and type. The progress that could be expected from selection with each index was shown.