Evaluation of the growth parameters of six commercial crossbred pig genotypes 1. Under commercial housing conditions in individual pens

Abstract

Simulation modelling is an active part of animal nutrition, which relies on mathematical functions to predict the performance of an animal. The Gompertz equation is one such function that is simple, but fits animal growth data well and when used in conjunction with allometry, can accurately predict the potential growth of an animal. When using this approach only three parameters are needed to sufficiently describe a genotype, viz. an estimate of mature size (protein weight at maturity - Pm), a rate of maturing (B) and an estimate of fatness (lipid:protein ratio at maturity - LPRm). The objective of this study was to estimate these parameters in South African commercial crossbred pigs under commercial environmental conditions. Thirty pigs each from six commercial genotypes were analysed using a serial slaughter method in which pigs were slaughtered at four and 14 days of age, and at 30, 40, 70, 80, 90 and 100 kg live weight. The animals were fed a choice between a high and low protein food and were housed in individual pens in two conventional open-sided housing facilities. The results indicated that there were no significant differences in mature weights or B of the various body chemical components between genotypes. This would support the use of a common set of growth parameters (B, Pm and LPRm of 0.0114±0.0005 /d, 40.0±1.86 kg, and 1.77±0.213 kg lipid/kg protein, respectively), inclusive of all commercial crossbred male pigs. However, the rate body lipid matures was significantly lower than the rate of other components within two genotypes. Evidence for the use of common allometric coefficients to define growth was inconclusive.