SEX DIFFERENCES IN CARCASS COMPOSITION AND TISSUE DISTRIBUTION IN MATURE DOUBLE MUSCLED CATTLE

Abstract

Nineteen mature Double Muscled (DM) cattle consisting of 11 cows and eight bulls were slaughtered between 470 and 710 kg to determine the influence of sex on carcass composition and muscle, bone and fat in DM cattle. Expressed as a percentage of the total side weight, DM bull carcasses had 15% more muscle and 55% less total fat. When sides were compared DM bulls showed a 17% increase in the muscle:bone ratio compared with DM cows. In bull carcasses, there were shifts in muscle weight distribution towards the forequarter. The ratio of hindquarter muscle:forequarter muscle was greater in cows than in bulls. Expressed as a percentage of the total side muscle, significant differences between sexes were found in 48 of the 95 muscles. The most striking sexual dimorphism was found in the neck region, particularly among the muscles responsible for secondary sexual features and those which act to elevate and extend the head. Sexual dimorphism was less pronounced in the distal parts of the both limbs. The cervical vertebrae and scapula made up a greater proportion of total side bone in DM bulls than in DM cows. There was a consistent but nonsignificant trend for the cows to have more of their bone caudally and less anteriorly compared with the bulls. Key words: Carcass composition, muscle distribution, bone distribution, mature Double Muscled cattle, double muscling