Data_Sheet_1_Effects of dietary tryptophan supplementation on rectal temperature, humoral immunity, and cecal microflora composition of heat-stressed broilers.ZIP

This trial aimed to determine the effects of tryptophan (Trp) on the rectal temperature, hormone, humoral immunity, and cecal microflora composition in broiler chickens under heat stress (HS). One hundred and eighty 18 days-old female Arbor Acres broilers were randomly divided into three treatment groups, with six replicates of ten birds in each replicate. The broilers were either raised under thermoneutral conditions (TN, 23 ± 1°C) or subjected to heat stress (34 ± 1°C for 8 h daily). The TN group received a basal diet, and another two heat-stressed groups were fed the basal diet (HS) or the basal diet supplemented with 0.18% Trp (HS + 0.18% Trp) for 21 consecutive days. The basal diet contained 0.18% Trp. Results revealed that HS increased the rectal temperature, serum epinephrine (EPI), and corticotropin-releasing hormone (CRH) concentrations (p < 0.05), reduced the bursal index, the levels of serum immunoglobulin A (IgA), IgG, IgM, and serotonin (5-HT) as well as the relative abundance of Actinobacteria in cecum (p < 0.05) compared with the TN group. Dietary supplementation of Trp decreased the rectal temperature, serum dopamine (DA), EPI, and the levels of CRH and L-kynurenine (p < 0.05), increased the bursal index, the levels of serum IgA, IgM, and 5-HT as well as the relative abundance of Ruminococcus torques group in cecum of heat-stressed broilers (p < 0.05) compared to HS group. In conclusion, dietary Trp supplementation decreased rectal temperature, improved cecal microbiota community and Trp metabolism, and enhanced humoral immunity of heat-stressed broilers.

本试验旨在探究色氨酸（tryptophan, Trp）对热应激（heat stress, HS）条件下肉鸡直肠温度、激素水平、体液免疫及盲肠微生物群组成的影响。选取180只18日龄雌性爱拔益加（Arbor Acres）肉鸡，随机分为3个处理组，每组设6个重复，每个重复含10只肉鸡。试验肉鸡分别饲养于热中性环境（thermoneutral conditions, TN，23±1℃）或热应激环境（每日34±1℃持续8小时）。其中TN组饲喂基础日粮，另外两个热应激组分别饲喂基础日粮（HS组）或添加0.18%色氨酸的基础日粮（HS+0.18% Trp组），试验周期为连续21天。基础日粮本身色氨酸含量为0.18%。试验结果显示：与TN组相比，HS组肉鸡直肠温度、血清肾上腺素（epinephrine, EPI）及促肾上腺皮质激素释放激素（corticotropin-releasing hormone, CRH）浓度均显著升高（p<0.05）；法氏囊指数、血清免疫球蛋白A（immunoglobulin A, IgA）、IgG、IgM及血清素（5-HT）水平，以及盲肠放线菌门（Actinobacteria）的相对丰度均显著降低（p<0.05）。与HS组相比，日粮添加色氨酸可显著降低热应激肉鸡的直肠温度、血清多巴胺（dopamine, DA）、EPI及CRH和L-犬尿氨酸（L-kynurenine）水平（p<0.05）；同时显著升高法氏囊指数、血清IgA、IgM及5-HT水平，以及盲肠瘤胃球菌扭矩群（Ruminococcus torques group）的相对丰度（p<0.05）。综上，日粮添加色氨酸可降低热应激肉鸡的直肠温度，改善其盲肠微生物群落结构与色氨酸代谢，并增强其体液免疫功能。