A quantitative assessment of reduced protein diets and supplements to improve nitrogen utilization

Several strategies are being developed to minimize nitrogen (N) pollution f rom poultry waste in areas with high concentrations of commercial poultry o perations. This study looks at the effects of using reduced protein (CP) di ets for broilers and layers housed under commercial conditions. Each of two broiler experiments involved 2400 birds; a layer experiment involved 1350 birds. The diets were based on practical ingredients, supplemented with com mercially available lysine, methionine, tryptophan, and threonine. Results indicated that similar broiler and layer performance could be maintained on reduced-CP diets as on conventional diets, although body fat content incre ased in broilers. The reduction in dietary CP content resulted in a 10-27% reduction in the total amount of N excreted during the 6-wk broiler rearing period. With layers, there was a 30%-35% reduction in daily N output. Redu ction in dietary CP level was associated with an improvement in DM (dry mat ter) and N retention. Accurate information on the AA composition of the die tary constituents is necessary, as is the addition of supplements of the li miting AA. Successful reduction in dietary CP content is likely to have mar ked beneficial effects in terms of reducing the N output in waste from poul try operations.