Evaluating the impact of excess dietary tryptophan on laying performance and immune function of laying hens reared under hot and humid summer conditions
XY Dong, MMM Azzam, W Rao, DY Yu… - British poultry …, 2012 - Taylor & Francis
XY Dong, MMM Azzam, W Rao, DY Yu, XT Zou
British poultry science, 2012•Taylor & Francis1. 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 …
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 …
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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