Over the years a large body of information has accumulated for the amino acid glycine, which prove that this amino acid is critical to animal nutrition in order for feeding to be more economic, eco-sustainable and supportive of animal health and food safety. Underpinning these glycine efficacies are its multifaceted metabolic interrelationships with other essential amino acids, and the resultant physiological responses. Key among these interactions is the inter-convertibility between glycine and serine, the participation of glycine in sulphur amino acid metabolism, and its biochemical linkages with arginine. Crucial to this is the metabolic release of glycine in threonine catabolism and cellular application in N detoxification- all linked to body amino acid homoeostasis. This is the first of a two-paper series reviewing the biochemistry and multifunctional metabolic involvements of glycine and the impacts on physiological efficiency of sulphur amino acids, threonine, arginine and total crude protein, mainly in broilers.
