Heat stress accounts for substantial economic loss in the poultry industry by altering the health and performance of chickens. Alpha-lipoic acid (ALA) is a water and fat-soluble antioxidant which is readily absorbed from the intestine resulting in maximum bioavailability. Moreover, ALA acts as a coenzyme in glucose metabolism and helps generate other antioxidants. Considering these benefits, we hypothesized that dietary supplementation of ALA would help mitigate heat stress in poultry. A total of 72 Day-old broiler chicks were randomly assigned into three treatment groups: no heat stress (NHS), heat stress with basal diet (HS), and heat stress with alpha-lipoic acid (HS+ALA); each treatment group had 6 replicate pens with 4 birds in each pen (n = 24/group). The allocated birds were raised under standard husbandry practices for 3 weeks. After 21 d, birds in the HS and HS+ALA groups were exposed to heat stress (33°C for 8 hours during the day) for 3 weeks, while the NHS group was reared under normal conditions (22-24°C). The HS+ALA group received a basal finisher diet fortified with ALA (500 mg/kg) during the treatment period (22 to 42 d), while other birds were provided with the basal finisher diet. Weekly body weight and feed intake were recorded. The cecum digesta for volatile fatty acids (VFAs) analysis and 16S rRNA sequencing for the gut microbiota analysis; and the ileum tissue samples for histological and gene expression analyses were collected on d 42. Exposure to heat stress decreased (P<0.05) average daily gain (ADG) and final body weight (FBW) in the HS group compared to the NHS group, the supplementation of ALA improved (P<0.05) ADG and FBW in heat-stressed birds. Furthermore, birds in the HS+ALA group had increased (P<0.05) expression of HSP90, PRDX1, GPX3, SOD2, OCLN, and MUC2 genes and higher (P<0.05) concentrations of major VFAs (acetate, propionate, and butyrate). The dietary ALA supplementation also improved the villus height and villus height to crypt depth ratio in the HS+ALA group. The microbial diversity analysis revealed significant abundance (P<0.05) of beneficial bacteria Lactobacillus and Peptostreptococcaceae in the cecum of the ALA group. These results indicate that dietary ALA supplementation effectively mitigates the negative effects of heat stress in broilers by improving the expression of heat-shock, tight-junction, antioxidants, and immune-related genes in the intestine, improving villus structures, increasing concentration of major VFAs, and enriching the beneficial microbiota.

中文翻译：

---

日粮中添加α-硫辛酸可减轻肉鸡热应激的负面影响。

通过改变鸡的健康和生产性能，热应激是家禽业的重大经济损失。α-硫辛酸 (ALA) 是一种水溶性和脂溶性抗氧化剂，很容易从肠道吸收，从而获得最大的生物利用度。此外，ALA 在葡萄糖代谢中充当辅酶，并有助于产生其他抗氧化剂。考虑到这些好处，我们假设膳食补充剂 ALA 将有助于减轻家禽的热应激。总共72日龄肉鸡被随机分配到三个处理组：无热应激（NHS）、基础日粮热应激（HS）和α-硫辛酸热应激（HS+ALA）；每个处理组有 6 个重复的围栏，每个围栏中有 4 只鸡（n = 24/组）。分配的鸟类在标准饲养实践下饲养 3 周。21 d后，HS 和 HS+ALA 组中的鸟类暴露于热应激（白天 33°C 8 小时）持续 3 周，而 NHS 组在正常条件下（22-24°C）饲养。HS+ALA 组在治疗期间（22 至 42 天）接受强化 ALA (500 mg/kg) 的基础育肥日粮，而其他鸡只接受基础育肥日粮。记录每周体重和采食量。用于挥发性脂肪酸 (VFA) 分析的盲肠食糜和用于肠道微生物群分析的 16S rRNA 测序；并且在第 42 天收集用于组织学和基因表达分析的回肠组织样本。与 NHS 组相比，HS 组的热应激暴露降低（P < 0.05）平均日增重（ADG）和最终体重（FBW），补充ALA改善（P<0.05）热应激鸟类的ADG和FBW。此外，HS+ALA 组中的鸟类 HSP90、PRDX1、GPX3、SOD2、OCLN 和 MUC2 基因的表达增加（P<0.05），主要 VFA（乙酸盐、丙酸盐和丁酸盐）浓度更高（P<0.05） . 膳食 ALA 补充剂还改善了 HS+ALA 组的绒毛高度和绒毛高度与隐窝深度的比率。微生物多样性分析显示，ALA 组盲肠中有益细菌乳酸杆菌和消化链球菌科的丰度显着（P<0.05）。这些结果表明，日粮中添加 ALA 可通过改善肠道中热休克、紧密连接、抗氧化剂和免疫相关基因的表达，改善绒毛结构，增加主要 VFA 的浓度，有效减轻肉鸡热应激的负面影响。 ,