Genomic analysis of purebred and crossbred Angus cattle demonstrates opportunity for multi-breed evaluation

Abstract

Context Overseas studies have quantified production differences of Hereford Angus crossbreds compared with purebred Angus for a range of traits including growth, carcass and reproductive traits. Aim This study aimed to quantify breed and heterosis effects using genomics. Methods Thirty Hereford and 30 Angus sires were mated to 1100 Angus cows and heifers in a large commercial herd run on pasture at Musselroe Bay, Tasmania. Approximately 1650 calves were born. Steers (743) were grown for an average of 23 months and then slaughtered. Results Heterozygosity effects were significant for birth, weaning and carcass weight and also loin eye-muscle area. On average, higher-quality (percentile) Hereford than Angus bulls were used. Breeding values were calculated for sires and could be compared with a common base given they also had BREEDPLAN breeding values published. Conclusions When heterozygosity was accounted for and when compared on a common base, progeny of average Angus sires were superior to progeny of Hereford sires for birthweight, carcass weight, eye-muscle area and intramuscular fat. Implications The method of benchmarking breeds using crossbred cattle and genomics provides a model for rapid adoption of multi-breed estimated breeding values, which is desirable for commercial beef producers.