The effect of breed-type and castration on muscle growth and distribution in cattle

Abstract

Data from carcasses of 210 cattle (119 bulls and 91 steers) from four breed-types, serially slaughtered from approximately 200 to 800 kg liveweight were used to test the hypothesis of similar gender dimorphism among breeds in relation to carcass muscle growth and distribution. Relative to total side muscle, breed types tended to have similar growth coefficients for all muscle groups, but differed significantly in the adjusted mean weights of 7 of the 9 muscle groups. Earlier maturing compared to later maturing breed-types had a lower proportion of the early maturing muscle groups and a higher proportion of the later maturing muscle groups. Gender dimorphism in relative growth rate was significant for 2 of the 9 muscle groups. At the same total side muscle, bulls as compared with steers showed a shift in muscle weight distribution towards the forequarter, similar proportion of muscle in the pistol and less proportion of muscle the in distal hindlimb and abdominal wall. Breed × gender interaction were only significant (though minor) for the proportion of muscle in the proximal hindlimb and the distal forelimb.