Muscle growth and development in the indigenous Nigerian pigs as influenced by age, sex and body weight

Abstract

SummaryMuscle growth was studied for 64 female, 64 castrated male and 64 intact male indigenous Nigerian pigs at 16 ages between birth and 672 days of age. Highly significant (P< 0·001) age differences were obtained for the proportion of total muscle, each muscle group and the 13 individually dissected (seven hind limb, two spinal column and four fore limb) muscles. Sex differences were significant (P< 0·05) for the proportion of total muscle and some of the individually dissected muscles.A highly significant (P< 0·01) increase in the rate of muscle deposition for each muscle group occurred between 56 and 112 days. Muscle deposition continued at the same rate up till 224 days of age before the peak was attained between 280 and 392 days when the average body weight was between 40·8 and 61·2 kg. A continuously significant (P< 0·05) decline in the rate of muscle deposition was obtained beyond 392 days of age. Growth coefficientsbcalculated from the linearly transformed allometric equation Y = aXbwere generally higher in the early phase of growth (0–168 days) than in later phases considered. However, growth coefficients obtained for the whole period revealed that apart from M. gastrocnemius, the other hind limb and spinal column muscles exhibited either ‘high’ or ‘average’ growth impetus. The fore limb muscles had growth coefficients significantly (P< 0·05) less than 1·00 and were therefore classified as having ‘low’ growth impetus. Generally, the intact male pigs showed superiority to the female and castrated male pigs in muscle growth and development.