Effect of energy intake on the performance of different types of pig from 45 to 100 kg body weight .1. Protein and lipid deposition

Between 45 and 100 kg body weight, Large White castrated males (cLW), and crossbred Pietrain x Large White castrated males (cPPX) and boars (bPPX) were either given food ad libitum in experiment 1 or allocated to four energy levels (0.70, 0.80, 0.90, 1.00 ad libitum) in experiment 2. Daily protein and amino acid supplies were calculated to be non-limiting for growth. Protein (PD) and lipid no) deposition rates were measured according to the comparative slaughter technique over the whole experimental period (experiments I and 2) and according to the nitrogen and energy balance technique at four stages of growth: 48, 64, 79 and 94 kg mean body weight (experiment 2). Average daily gain increased linearly with metabolizable energy (ME) intake, the slope of the relationship being significantly different between types of pig (from +28 to +36 g per additional MJ ME). Daily PD increased with ME intake above maintenance (MEp) according to a linear-plateau relationship in the three types of pig: the slope was significantly affected by type of pig (from +3.4 to 6.0 g per extra MJ MEp) but not by stage of growth. Daily LD increased linearly with MEp intake; neither the type of pig nor the stage of growth affected its slope (+13.5 g per extra MJ MEp). The LD/PD ratio in the extra body-weight gain associated with increased energy intake was affected only by the type of pig.