The effect of increasing slaughter weight on the production performance and meat quality of finishing pigs

A study was made in two parts to establish the production performance poten tial of pigs taken to heavy slaughter weights (a) in individual housing and (b) in group housing. In experiment 1 96 crossbred pigs, comprised of equa l numbers of boars, castrated males and gilts, were housed individually fro m 50 kg live weight and offered food ad libitum until one of four target sl aughter weights was reached (70, 80, 90 or 100 kg carcass weight). Detailed dissection and meat quality assessments were performed on sample joints ta ken from these pigs. There were significant interactions in that boars main tained a high level of food conversion efficiency while this deteriorated a t heavier weights for castrated males and gilts. Protein deposition rates ( PDR) were estimated to be close to, or in excess of, 200 g/day for boars. D aily live-weight gains were similar at all four slaughter weights despite i ncreases (P < 0.001) in daily food intake at the heavier weights. Sample jo int contents of lean (P < 0.05) and bone (P = 0.001) decreased while subcut aneous fat content increased (P < 0.001) with increasing slaughter weight. Cooking loss was reduced (P < 0.001) at the heavier weights while other mea t quality parameters were not significantly affected by slaughter weight or gender. In experiment 2 288 group-housed boars and gilts were slaughtered at the same four target carcass weights as in experiment 1. Daily food inta ke, daily live-weight gain and variability in performance were lower for gr oup-housed animals. It is concluded that maximum lean growth lies beyond ad libitum food intake for group-housed pigs of the genotype used in the pres ent study. There are opportunities to take pigs to high slaughter weights w ith no reduction in daily live-weight gain and concomitant improvements in some aspects of meat quality.