The influence of dietary protein and energy intake on the performance, body composition and energy utilization of pigs growing from 7 to 19 kg

Abstract

ABSTRACTThirty-six entire male pigs were used to investigate the effects of two levels of dietary crude protein (150 and 220 g/kg) each in combination with four levels of feeding (1·0, 1·32, 1·64 MJ digestible energy/kg M0·73per day andad libitum) on growth, body composition and energy utilization over the live-weight range 7 to 19 kg.Growth rate responded linearly (P< 0·001) to increasing energy intake but was depressed (P< 0·05) when dietary crude protein was reduced from 220 to 150 g/kg.Raising digestible energy intake increased and decreased respectively the proportions of fat and protein in the empty body at 19 kg live weight. However, the magnitude of the response of both components to change in digestible energy intake was reduced in the case of pigs fed the lower protein diet.Total energy retained and that retained as fat and as protein responded linearly (P< 0·001) to change in digestible energy intake of either diet. Extrapolation of the regression of total energy retained on digestible energy intake yielded a digestible energy requirement for maintenance of 510 kJ/kg M0·75per day, which was unaffected by level of dietary protein.The partial efficiencies of protein utilization, estimated from the regressions of protein deposition (g/day) on protein intake (g/day), were 0·616 and 0·411 for pigs given the diets containing 150 and 220 g crude protein per kg respectively.