The growth of muscle, bone, fat and connective tissue in cattle from 150 days’ gestation to 84 days old

The growth of muscle, bone, fat and connective tissue was investigated in 30 half-sib Friesian foetuses and calves over five age phases from 150 days’ gestation to 84 days old. Large changes in the growth coefficients of all four carcass tissues and most of the ‘standard muscle groups’ over the pre-natal growth phases confirmed this as a period of intense differential growth. Changes in the growth coefficients of muscle, bone and connective tissue showed that the post-natal growth patterns of these tissues differed greatly from their pre-natal growth patterns and were generally established by birth. Most large changes in growth impetus of the nine ‘standard muscle groups’ were observed in the pre-natal growth period, some further changes occurring up to 28 days post-natally. There were no significant changes in growth impetus of the muscle groups in the two growth phases beyond 28 days. High standard errors were associated with the growth coefficients of most fat depots and total dissected fat, reflecting the large variation in depot fatness and carcass fatness among animals of similar age. Problems associated with the dissection of fatty tissues made it difficult to interpret the growth of fat from 150 days’ gestation to 84 days old. A functional basis is postulated for the growth of muscle, bone and connective tissue and for growth within the musculature