The effect of pre- and post-natal nutrition on the growth of beef cattle. 3. The effect of severe restriction in early post-natal life on the development of the body components and chemical composition

Abstract

The effects of restricted growth of cattle both before and after birth, of the method of their realimentation, and of sex on (1) body and carcass composition, (2) the weights of visceral components, (3) the weights of selected individual muscles and bones, and (4) the heights of the animals at the withers and pelvis were ascertained. Castrate male and entire female cattle were slaughtered when their liveweights reached 400 and 370 kg respectively. Other male and female calves were slaughtered at 200 days of age following a controlled feeding period on either a high or a low plane diet. Although pre-natal nutrition significantly (P < 0.05) affected the height of the calves at 3 days of age, it had no lasting effect on this or other components. When adjusted to the same empty body weight or carcass weight, animals restricted in growth then intensively realimented had (P < 0.01) more fat and less protein, water and ash than animals unrestricted in growth and later fed intensively. Animals finished on pasture had (P < 0.01) less fat and more protein, water and ash than the intensively finished calves, but their composition was unaffected by the controlled feeding treatments. Significant differences (P < 0.01) between restricted and unrestricted animals in the percentage water or protein in the fat-free mass at the end of the controlled feeding period were eliminated when the animals had recovered. The weights of visceral components, individual muscles and bones were not influenced by the level of nutrition during the controlled feeding period. Animals finished on pasture had (P < 0.01) more blood, heavier livers, heavier individual muscles and bones than the intensively finished animals. They also had (P < 0.01) lighter fasted liveweight, empty body weight, hot carcass weight, dressing percentage and heavier wet rumen-reticulum contents than the intensively finished cattle. Although the pasture finished animals were (P < 0.01) shorter at 200 and 300 days of age than the intensively finished animals, they were (P < 0.01) taller just prior to slaughter. It is suggested that meat-producing animals can overcome restrictions imposed on growth immediately after birth to attain marketable weight on either pasture or intensive feeding.