Abstract
The present paper gives a general overview on amino acid nutrition mainly focused on the concept of ideal protein and amino acid requirements in swine and poultry. Also, the nutritional, economic and environmental roles of synthetic amino acids are presented. A special emphasis has been given to the protein sparing effect by the supplementation of synthetic amino acids into diet and to the effect of this supplementation on growth performance and reduction of environmental pollutants in swine and poultry manure. It is concluded that the supplementation of limited amounts of synthetic amino acids (0.1 to 0.3%) to diets for swine and poultry could spare 2 to 3 percentage units of dietary protein and substantially reduce nutrient excretion, especially nitrogen. Immunocompetency as affected by amino acid nutrition is also introduced and the importance of threonine for the synthesis of immunoproteins in colostrum and milk to maintain piglets' health and intestinal integrity has been emphasized. Finally, some speculation on the future of global amino acids market is presented in conclusion.