Individual and Maternal Genetic Effects for Beef Carcass Traits of Breeds Representing Diverse Biological Types (Cycle I)

Abstract

Individual (gI) and maternal (gM) average genetic effects and individual (hI) and maternal (hM) heterosis effects for carcass characteristics of Angus, Hereford, Jersey, South Devon, Limousin, Simmental and Charolais were estimated from crosses sired by these breeds and from Angus and Hereford dams. First cross (F1) progeny (N = 1,120) and the steer and heifer progeny of F1 dams (N = 1,204) were used in the analyses. There was significantly more variation among breeds associated with gI than with gM. Individual heterosis effects were significant for all traits except intramuscular and kidney fat. Maternal heterosis was significant for carcass weight and carcass composition. The sum of gI and gM, which corresponds to expected differences among purebreds, differed significantly. Angus and Hereford were similar for all traits, except the greater intramuscular fat of Angus, and were characterized by below average final and carcass weights and percentages of retail product and bone, but were above average in fat cover, intramuscular fat and fat trim. Jersey had the lowest final and carcass weights and percentage of retail product of the breeds evaluated, and below average bone, was intermediate in fat cover, but had the greatest amount of intramuscular and kidney fat. Charolais and Simmental did not differ significantly for any trait and were characterized by having high final and carcass weights, retail product and bone percentages and low fat cover, intramuscular fat and fat trim. Limousin had final and carcass weights that were similar to Angus and Hereford, but intramuscular fat and carcass composition that were similar to Charolais. South Devon tended to rank between the averages of Charolais and Simmental and of Angus and Hereford.