title: Evaluating the impact of excess dietary tryptophan on laying performance and immune function of laying hens reared under hot and humid summer conditions.
abstract: 1. Tryptophan (Trp), besides its role as an essential amino acid in protein synthesis, may also have other important effects on laying hens under summer conditions.   2. Babcock Brown layers (n = 768), 40 weeks of age, were allocated to 4 treatment groups, each of which included 6 replicates of 32 hens. Each group received the same basal diet, formulated with maize and soybean meal, for 8 weeks. Hens were fed on the basal diet with 0·0, 0·2, 0·4, and 0·8 g/kg L-Trp to achieve dietary concentrations of 1·7, 1·9 g/kg, 2·1 g/kg or 2·5 g/kg of Trp, respectively.   3. Supplementing L-Trp had no affect on laying performance. Adding 0·2 or 0·4 g/kg L-Trp improved egg shell strength compared with those fed on the control diet. Serum albumin concentration increased at 0·4 g/kg compared with those receiving 0·0 or 0·8 g/kg Trp. The addition of Trp at 0·4 g/kg increased serum IgM concentration quadratically. Serum superoxide dismutase (T-SOD) increased linearly and quadratically at 0·4 g/kg.   4. In conclusion, we suggest that 0·2 to 0·4 g/kg Trp may have beneficial effects on laying hens under conditions of high temperature and humidity.
authors.affiliation: Feed Science Institute, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: X Y
authors.initials: XY
authors.lastname: Dong
authors.forename: M M M
authors.initials: MM
authors.lastname: Azzam
authors.forename: W
authors.initials: W
authors.lastname: Rao
authors.forename: D Y
authors.initials: DY
authors.lastname: Yu
authors.forename: X T
authors.initials: XT
authors.lastname: Zou
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001774:Blood Chemical Analysis / Q000662:veterinary; D002645:Chickens / Q000276:immunology / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis*; D005260:Female; D006358:Hot Temperature; D006813:Humidity; D010063:Ovum / Q000502:physiology; D012098:Reproduction / Q000187:drug effects; D012701:Serotonin / Q000097:blood; D014364:Tryptophan / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D012701:Serotonin; D014364:Tryptophan