ABSTRACTForty-five piglets were used to study the effects of feeding diets containing 153, 239 or 321 g crude protein per kg dry matter between 1·8 and 6·5 kg live weight, and low and high protein diets subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of skeletal muscle to 45 kg live weight.Reducing dietary crude protein between 1·8 and 6·5 kg live weight depressed growth performance and at 6·5 kg live weight increased body fat content but reduced body protein, body water and the weight and DNA content of the adductor muscle. The effects of dietary protein content before 6·5 kg live weight on body composition at the latter weight were still evident in pigs killed at 11·5 kg live weight whilst the differences in muscle DNA persisted to 45 kg live weight.On the lower protein treatment subsequent to 6·5 kg live weight there was a tendency for pigs given the lowest protein diet before 6-5 kg live weight to exhibit better growth performance and deposit protein at a faster rate than those given the higher protein diets. However, these responses were reversed on the higher protein treatment subsequent to 6·5 kg live weight.The effects of dietary protein content subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of muscle tissue were qualitatively the same as those for the live-weight phase 1·8 to 6·5 kg.
Effects of low-crude protein diets supplemented with arginine, glutamine, threonine, and methionine on regulating nutrient absorption, intestinal health, and growth performance of Eimeria-infected chickens
