Influence of Reproductive Management Factors on Genetic Merit of Service Sires

Abstract

Records were terminated (by sale or dry date) lactation records for cows on DHI test in Virginia for 1982 through 1984. July 1986 production evaluations, most recent type evaluations, and appropriate semen prices for date of service for AI bulls were merged with service sire identification from 384,990 DHI records. Repeat breedings and multiple lactations per cow were used. Least squares procedures revealed significant influences of season, mate's sire's PD for type and dollars, mate's milk yield deviation, registry status, and insemination number on production evaluations, PD type, and semen price of service sire. Significant effects of several of the same variables on linear type traits were observed. Season effects were possibly due to genetic trends. Genetic merit for production and type of service sire declined for daughters of sires with missing or low type and production evaluations, for mates with low or missing herdmate deviations, for grade cows, and for repeat services, especially fourth and later. Days between breedings were nonsignificant or of limited importance in predicting genetic merit of service sires. Proven bulls in AI accounted for 76.3% of all breedings, AI sample sires for 6.3%, and non-AI or unknown sires for 17.4% of breedings in these data.