[Frontiers in Bioscience S3, 286-297, January 1, 2011]
Tryptophan metabolism in animals: important roles in nutrition and health
Yu-long Yin1, Ze-Meng Feng 1,4, Zhi-Ru Tang1, Guoyao Wu1,3,5
1Hunan Engineering and Research Center of Animal and Poultry Science and Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, China 410125,2College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China 410125,3Department of Animal Science, Texas A&M University, College Station, TX, USA 77843-2471,4Graduate School of the Chinese Academy of Sciences, Beijing 100039, China, 5State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China 100193
TABLE OF CONTENTS
L-Tryptophan is a nutritionally essential amino acid for monogastric animals and preweaning ruminants because it cannot be synthesized in the body. Besides serving as a building block for proteins, tryptophan is a critical nutrient for the functions of nervous and immune systems. Over the past decades, much attention has been directed to study the role of tryptophan as a limiting amino acid in mammalian and avian nutrition. However, emerging evidence from recent studies shows that tryptophan and its metabolites (e.g., serotonin (5-hydroxytryptamine, 5-HT) and melatonin)) can regulate feed intake, reproduction, immunity, neurological function, and anti-stress responses. Additionally, tryptophan may modulate gene expression and nutrient metabolism to impact whole-body homeostasis in organisms. Thus, adequate intake of this amino acid from the diet is crucial for growth, development, and health of animals and humans.