A reappraisal of amino acids in broiler chicken nutrition

SUMMARY The purpose of the review is to reappraise amino acids in broiler chicken nutrition so that the chicken-meat industry may be better placed to enhance the utilisation of protein and amino acids by broiler chickens. The quest to develop reduced-crude protein diets emphasises the dichotomy between protein-bound and non-protein-bound (synthetic, crystalline) amino acids with respect to digestive dynamics. The successful development and adoption of reduced-crude protein diets will almost certainly demand a superior knowledge of amino acids in broiler chicken nutrition than is presently the case. Consequently, there is a need to identify the shortfalls in our comprehension so that they may be corrected. The intestinal uptakes of amino acids and their transition across enterocytes along the small intestine to enter the portal circulation is an area that is poorly understood. Similarly, this applies to protein turnover and the post-enteral metabolism and partitioning of amino acids into protein body segments. Feathering demands about 10% of dietary amino acids in broiler chickens, but the amino acid profile of feathers is radically different to that of skeletal muscle. The likelihood is that more attention should be paid to the amino acid requirements of feathering, more so when birds are offered reduced-crude protein diets because there is the possibility that preference is given to partitioning of amino acids for feathering. Reduced-crude protein diets hold several potential advantages including reduced nitrogen and ammonia emissions and a decreased dependence on soybean meal as a major source of protein. Hence, the need for a better comprehension of amino acids in broiler chicken nutrition.