Effect of dietary energy level and weaning weight on body composition and efficiency of energy utilization in weanling piglets

Abstract Text: The experiment was conducted to evaluate the effects of dietary ME and weaning weight (WW) on body composition and energy utilization in weanling piglets. Thirty two male piglets were classified according to their WW as light (4.5 ± 0.4 kg) or heavy (6.7 ± 0.5 kg), and housed individually in metabolic cages for 28 d. Six treatments, 2 WW and 3 ME (I: 3,400; II: 3,600; and III: 3,800 kcal/kg) with constant Lys:ME were used. The control diet (I) was formulated with standard energy and nutrient recommendations (Brazilian Tables for Poultry and Swine), whereas AA, Ca, P, and lactose levels in the diet II and III were adjusted for the increased ME. Body composition, energy and nutrient deposition rates, and energy efficiency of gain were measured through comparative slaughter technique. There were no WW x ME interactions for any of the responses. BW, ADFI, and ADG were greater (P < 0.05) in piglets with heavier WW than lighter WW, but there was no difference in G:F. Also, heavy WW piglets had greater fasted BW, eviscerated carcass and empty BW (EBW),  compared to light WW piglets (P < 0.05), but there was no difference in the organ + blood (OB) fraction. When those responses were equalized per kilogram of fasted BW, light WW piglets had greater OB than heavy WW piglets. Gastrointestinal tract and kidneys were greater in heavy WW piglets, while urinary tract and blood were greater in light WW piglets when equalized per kilogram of fasted BW (P < 0.05). There was no effect of ME on physical body composition, and ME and WW did not affect chemical body composition. The rates of water, ash, and protein deposition in the carcass and OB were greater in heavy WW piglets (P < 0.05). Water and protein deposition in EBW also were greater in heavy WW piglets (P < 0.05). Increasing ME did not affect energy and nutrient deposition rates in any of the body fractions. Heavy WW piglets had greater intakes of ME, with higher estimates of ME for maintenance and heat production (P < 0.05). Energy efficiency was not affected by the WW or ME content of the diets. In conclusion, heavy WW piglets had greater protein deposition and efficiency of gain than light WW piglets. The ME level did not improve the response criteria evaluated in the current study.

Keywords: energy deposition, metabolizable energy, weaning weight