Present status of the use of digestible amino acid values in formulation of broiler diets: Opportunities and obstacles

The use of digestible amino acid values for more efficient formulation of broiler diets is of growing interest among nutritionists. Methodology of determination of digestible amino acids, coupled with the high cost of amino acid analysis, has limited the scope of investigations among researchers worldwide. The sensitivity of most protein supplements to differences in processing conditions hampers development of "universal" digestibility values. A study was conducted to evaluate the application of digestible amino acids to formulation of diets for broiler chickens. Diets were formulated using either a simple (corn-soybean meal) or complex (corn-soybean meal-peanut meal-corn gluten meal) set of ingredients. The amino acids in peanut meal are less well digested than these in soybean meal. Diets in each series were formulated either on a total amino acid basis or with digestible amino acids set as different percentages of total amino acid requirements suggested by NRC (1994). When formulated on total amino acid basis, birds fed "simple" diets performed significantly better than birds fed "complex" diets. However, when formulated on a digestible amino acid basis, no significant differences in performance were observed between birds fed the two different types of diets. Thus, utilizing digestible amino acid values should enhance utilization of protein sources that are less well digested than soybean meal. Application of amino acid digestibility techniques to improve the utilization of feather meal, a protein source known to be of poor biological value, did not improve the utilization of this ingredient in broiler diets. Thus, care should be taken in utilizing increased amounts of protein supplements known to be of reduced amino acid availability when formulating diets for poultry.