Consideration of mates in ranking Guernsey sires for type [Bulls]

A Chi-square test of goodness of fit indicated that many Guernsey sires had mates not representative of the population. Mates effect on sire ranking by progeny records, therefore, was examined for each of 12 traits of body conformation. Sire rankings from two models including a random sire factor and fixed age, month, and herd-year factors were compared. One model contained dam's score as a covariate. Eighty sires having 33,634 daughters with first scores were in the analysis. Addition of mate's score as a covariate did not change appreciably sire ranking when all progeny were included. For the 12 traits, Spearman's rank correlations were in excess of .99.