EFFECTIVENESS OF SIRE PROOFS IN PREDICTING RESULTS OF CORRECTIVE MATINGS FOR CONFORMATION IN CANADIAN HOLSTEIN-FRIESIAN CATTLE

Abstract

Type classification records of maternal half-sister pairs were analyzed to determine if "Superior" sires differed significantly from "Inferior" sires in their progeny distributions for each type component. "Superior" sires differed by at least one standard deviation in proofs from "Inferior" sires. The sires contrasted were 53 Holstein-Friesian bulls which entered Canadian Artificial Insemination units between 1956 and 1962. Data were analyzed separately for each component of the scorecard and for each classification rating of the dam. Chi-square tests showed highly significant (P <.01) differences in the progeny distributions for the two groups of sires. Differences were most dramatic for size, rump, body capacity and dairy character. In general, higher chi-square values were found for traits with higher heritability estimates. Correlations between sires’ proofs for conformation at the time of mating and their mates’ conformation records for major scorecard components were all positive and highly significant (P <.01) except for dairy character. This indicates that assortative matings are taking place and thus it is essential to adjust for mates of sires to generate accurate sire ratings for conformation.