Evaluating the impact of excess dietary tryptophan on laying performance and immune function of laying hens reared under hot and humid summer conditions |
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| Authors: | XY Dong MMM Azzam W Rao DY Yu |
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| Institution: | 1. Feed Science Institute, Zhejiang University, Zijingang Campus , Hangzhou, 310058 , China;2. Feed Science Institute, Zhejiang University, Zijingang Campus , Hangzhou, 310058 , China;3. Poultry Production Department , Mansoura University , Mansoura 35516 , Egypt |
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| 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. |
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