The influence of changes in tissue shape on muscle: bone ratio in growing sheep

Extract

Muscle: bone ratio is a term commonly used in studies of growth and meat production. It is perceived to affect carcass value (Kempster et al., 1982) even though it is positively correlated with the fat: muscle ratio. Both ratios increase during post-natal growth but the literature is lacking in a detailed description of how this occurs.

Bone and muscle are closely related due to their roles in movement. Much evidence exists to support the hypothesis of Hooper (1978) that bone is the “pacemaker” for muscle growth. Certainly, muscle appears to display a more passive role in growth, responding to changes in length or loading by altering its length and diameter (eg. Holly et al., 1980; Sivachelvan and Davies, 1986), while bone growth in length is progressive and finite, appearing to follow a genetically determined plan. Thus the fundamental importance of bone to growth of muscle cannot be over-emphasized.

Relatively greater increases in diameter than in length occur during post-natal growth of bone and muscle. The relative magnitude of these changes has been little studied due, in part, to the difficulty in definition of shape. Consequently conformation has normally been quantified subjectively or indirectly in terms of weight.