Aspects of linear growth of muscles in the indigenous Nigerian pig.

The development of the length of 2 spinal column, 7 hind limb, and 4 fore limb muscles of one body half were investigated in 64 female, male, and castrated male indigenous Nigerian pigs each from birth to 627 days of age. While the muscle lengths increased significantly (P less than 0.001) with age, non-significant sex influences (P greater than 0.05) were obtained except for M. gastrocnemius and M. infraspinatus. The rate of longitudinal growth in muscles was greatest between the birth and 112 days of age. The ratio of linear equivalence (cubic root) of the muscle weights to muscle lengths indicated the proportionate increase in transverse growth relative to longitudinal growth. Generally, these ratios were higher in the earlier than in the later phase of growth and stabilized between 112 and 448 days post natal. Linear modelling of the growth gave highest values for male and lowest values for castrated animals. Muscle length growth was more closely related to body weight than to chronological age. Estimates of the longissimus dorsi muscle diameter were highly related to the body weight (R2 = 0.96), with intact male pigs exhibiting the highest growth potential in this parameter.