Studies of growth and development in the young pig Part I. The carcass composition at 56 days of age of pigs reared along different growth curves

1. A comparison was made of the carcass composition at 56 days of age of early-weaned pigs grown along predetermined growth curves to 30, 40 and 50 lb. live weight and of suckled pigs grown to 50 lb. live weight at 56 days of age.Eight blocks of four pigs were slaughtered when 56 days old and comprehensive carcass dissections undertaken.2. There were no differences in the proportionate weight of the joints or of individual bones between the suckled and early-weaned pigs weighing 50 lb. at 56 days of age.The difference in the proportionate weights of the joints between the three groups of early-weaned pigs reflected the change in development which took place with increasing live weight. There was, however, no clear gradient of development along the bones of the limbs with increasing weight at 56 days of age.3. The dissected joints (hams, shoulders, neck, pelvis and loin) from the early-weaned pigs which weighed 50 lb. live weight contained 0·5% less bone, 1·5% less muscle and 1·7% more fat than the carcasses of suckled pigs reared to 50 lb. at 56 days of age.The dissected joints of the early-weaned pigs reared to 30 lb. at 56 days of age contained 1·4% more bone, 2·7% more muscle and 5·3% less fat than the joints of the early-weaned pigs reared to 40 lb. and 2·6% more bone, 5·2% more muscle and 8·8% less fat than the joints of early-weaned pigs reared to 50 lb.