Compensatory growth in sheep

Abstract

Some attributes of the body composition of Dorset Horn x Merino wethers, which were either continuously grown or subjected to one or two periods of starvation-weight loss, realimentation and compensatory growth, were studied. Periods of restricted feed intake were imposed when liveweights were either below (23 kg) or above (43 kg) the level generally regarded as a mature liveweight (c. 31 kg) for such sheep. Loss of liveweight resulted in different responses in the meat of immature and mature animals. The meat from immature sheep was depleted of fat, whereas that from mature sheep increased in fat content. Loss of fat from the meat of immature sheep was associated with both atrophy and hypoplasia of the subcutaneous adipose cells, but in mature sheep there was atrophy without hypoplasia of these adipose cells. Although the greatest loss of fat was from the meat, proportionately more fat was lost from the offal, particularly in mature sheep. The amount of protein in the carcass meat was similar in control, starved, or realimented sheep of the same body weight. During the first few days of realimentation the sheep consumed three to four times as much food per day as during the starvation periods; the apparent digestibility of the food was increased from 53–68% to 80–90%; liveweight gain was 500–600 g/day, and there were increases in fat, water and protein in the meat of realimented animals. Sheep which had been starved and realimented, either once or twice, rapidly achieved liveweights equal to those of continuously grown animals and were similar to them in both body and meat composition.