Muscle and bone distribution in mature normal and double muscled cows

Abstract

Muscle and bone distribution was examined in 11 mature Double Muscled and 12 mature normal muscled (Beef Synthetic) cows which were slaughtered between 470 and 620 kg liveweight. Expressed as a percentage of total side muscle significant differences between Double Muscled and normal cows were found in 42 of the 95 muscles and in four of the nine anatomical muscle groups. In Double Muscled carcasses there were shifts in muscle weight distribution towards the more fleshy, expensive and superficial muscles. Double Muscled cows had proportionately less muscle in the distal hindlimb, distal forelimb, deep muscles in the thicker parts of the carcass and neck muscles than normal cows. Muscular hypertrophy revealed an increasing inner-outer gradient across the muscle layers, with the superficial and bulkiest muscles being the most hypertrophied. The humerus, carpus and os coxa of the Double Muscled cows formed lower proportions of total bone weight than they did in normal cows. Along the vertebral column Double Muscled cows had greater percentages of lumbar and thoracic vertebrae than normal cows but a smaller percentage of cervical vertebrae though the differences were not significant ( P > 0.05).