Studies on Performance Testing for Growth Rate of Dual Purpose Bulls

Abstract

Abstract A Mixed Model Procedure was applied to the evaluation of growth rate of performance-tested dual-purpose bulls in Sweden. The model used included the effects of test station, year and season of birth of bulls, sire group, sire, and bull within sire. Components of variance for sire and error were estimated for daily gain. The sire variance was rather smaller in the Swedish Red and White breed (SRB) than in Swedish Friesian (SLB), while error variances were of the same order in both breeds. The heritability for daily gain was estimated to 0.29 in SRB and 0.38 in SLB. Correlations between breeding values for daily gain by BLUP and by the Contemporary Comparison method so far used in Sweden were 0.88 for SRB and 0.83 for SLB. The genetic progress in daily gain was fairly small in both breeds, but especially so in SLB. Selection differentials between bulls accepted for AI and all performance-tested bulls were on average 10–12 g/day, corresponding to 20% of the bulls tested for daily gain being culled d...