Prenatal and postnatal influences on growth and fat measurements in swine

Data from 153 foster groups, each consisting of a dam and a nurse, were analyzed separately for breed (Lacombe, Yorkshire) parity (first, second), and sex of piglet (boar, gilt) to estimate prenatal, postnatal and prenatal X postnatal influences on growth and fat measurements. Significant differences were not observed between breeds, parity and sex of piglets; the estimates were pooled over these traits. Prenatal effects were the major contributing factor in the determination of preweaning growth rate, weaning weight, postweaning average daily gain and allometric growth coefficient, rib and loin fat deposition coefficients. Postnatal influence was of minor importance and the prenatal X postnatal interaction was of negligible consequence. These observations indicated that crossfostering of piglets between parities and breeds without regard for the sex of the piglet would not seriously bias subsequent performance testing results. Heritability estimates for weaning weight, postweaning growth rate and backfat thickness differed from published values.