This study was conducted to evaluate the effects of dietary metabolisable energy (ME: 3.25, 3.40, 3.55, or 3.70 Mcal kg−1) and weaning weight (WW: light 4.0±0.7 kg, and heavy: 6.3±0.6 kg) on productive response and energy utilization of weaned piglets. Sixty-four male piglets were housed in 32 metabolic cages (two animals per cage) during the first 14 d postweaning. At day 15, only one animal per cage was kept until day 28. Body composition, energy, and nutrient deposition rates and energy utilization efficiency were measured through a comparative slaughter procedure. Piglets with light WW had a poorer feed conversion ratio and lower weight gain and feed intake when expressed per live weight. Increased ME led to greater daily fat deposition in the empty bodies (defined as weighted mean of the carcass + organs + blood, no intestinal content), while light WW piglets had a reduced protein deposition. Light WW piglets increased heat production with increased ME, but no effect was seen for the heavy WW piglets. By contrast, heavy WW piglets increased empty body gross energy as ME increased, while no influence was observed on light WW piglets. Increasing dietary energy levels did not contribute to the subsequent growth performance of piglets that were lighter at weaning. The lack of interaction between weaning weight and dietary ME content on growth performance does not support the hypothesis that light piglets at weaning do not exhibit compensatory growth because of limitations in energy intake.
metabolism; pig nutrition; protein:energy ratio; tissue deposition