C H a N G E S in Swine Body Composit Ion from Birth to 145 Kg 1'2

An experiment using 81 crossbred swine was conducted to evaluate quantitative and percentage chemical compositional changes of swine from 1.5 kg (birth) to 145 kg body weight. Groups of eight pigs were sacrificed at 1.5, 6.4 and 18 kg, and then at 18 kg increments to 145 kg. Body composit ion was determined by grinding the entire body, minus digesta, partit ioning the carcass from other body components and chemically analyzing each subsample. Results indicated that weight of the carcass increased linearly with live weight, while the total weight of the other body components increased quadratically. Percentage fat in the empty body (ingesta-free) increased rapidly from birth to weaning (6.4 kg), plateaued until 36 kg and then increased, while water percentage declined dramatically from 1.5 to 6.4 kg, but then declined more gradually to 145 kg. Percentage protein increased from birth to 18 kg, plateaued and declined after 54 kg. When expressed on a fat-free basis, the percentage water decreased in a curvilinear manner with increasing animal weight while protein increased curvilinearly inverse to the change in water. Constancy of composition ("chemical matur i ty") between protein and water in the fat-free body was not attained by 145 kg. When expressed on an absolute empty body basis, water, protein and fat weight increased