Comparison of Genetic Group and Relationship Methods for Mixed Model Sire Evaluation

Abstract

Mixed model procedures for sire evaluation were used to evaluate 52 sires by the method of grouping bulls according to year of entry into service and by the method of accounting for relationships among sires. A total of 3288 first lactation 305-day Holstein records of milk yield and composition was used to compare the two methods. Pedigrees of all sires were traced two generations for numerator relationships between the sires. Only 8 sires were not related to any other. Each of the remaining 44 sires was related to at least one other; some were related to as man)/ as 16 others. Four sires were inbred. Rank correlations between sire proofs by the two methods were .88, .89, .91, .91, and .93 for milk, fat, and protein yield, and fat and protein percent. Error variances of prediction of sire proofs by groups averaged 18% and 11% larger than those of relationships for yield and composition traits. Accounting for relationships was particularly effective in reducing error variances of prediction for sires that had few daughters.