Body composition of piglets exhibiting different growth rates
The growth and composition of the neonatal pig is of interest because of potential impact on subsequent growth and finally, composition at market weight. The purpose of this study was to compare at weaning the growth and body composition of the largest and smallest pigs from each of 38 litters. At weaning (27±1.7 d) the largest (9.3±1.1 kg) and smallest (6.2±1.5 kg) pigs were selected for body composition measurement by dual energy X-ray absorptiometry (DXA). The body composition of the largest pigs consisted of 38 % more fat, 32 % more lean, and 29 % more bone mineral content ( P<0.001). However, when expressed as a percentage of body weight, there was no difference in the fat, lean or bone mineral content content of the two groups of pigs ( P>0.05). A second study consisted of 12 pairs of pigs from 8 litters that were selected on the basis of having the same birth weight, but one pig out gaining the other by at least 50 g/day. At 21 days of age the selected pigs were scanned by DXA. For both groups combined, the correlation (r) between body weight and lean mass was 0.99, between body weight and fat mass it was 0.87, and between body weight at birth and body weight at weaning it was 0.56. The results of these studies revealed that, at weaning, the fastest and slowest growing pigs had similar proportions of fat, lean and bone mineral and, consistent with previous results, the rates of both fat and lean deposition were highly correlated ( P<0.001) with total body growth rate.