To evaluate the ameliorative effect of algae-derived polysaccharide (ADP) supplementation on duodenal injury caused by heat stress (HS) in broilers, a total of 144 male yellow-feathered broilers (56-day-old) were randomly allocated into three groups: The TN group (thermoneutral zone, broilers were raised at 23.6 ± 1.8 °C); HS group (heat stress, broilers were exposed to 33.2 ± 1.5 °C 10 h/day, 8:00 a.m.–18:00 p.m., the temperature in the remaining period was consistent with the TN group); HSA group (heat-stressed broilers were fed with ADP supplemented diet at 1000 mg/kg). There were six replications in each treatment, and eight broilers in each replication. The feeding trial lasted four weeks. The results showed that dietary ADP supplementation tended to increase the villus height (p = 0.077) and villus width (p = 0.062), and decrease the apoptosis rate (p = 0.081) in the duodenum of broilers under HS. Furthermore, dietary ADP increased the relative mRNA and protein (based on immunofluorescence) expression levels of occludin and zonula occludens-1 (ZO-1) in the duodenum of broilers under HS (p < 0.05). In addition, dietary ADP enhanced the total antioxidation capacity (T-AOC) and activity of glutathione-S transferase (GST), while reducing the malondialdehyde (MDA) concentration of the duodenum in broilers under HS (p < 0.05). Moreover, dietary ADP supplementation upregulated the duodenal nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), glutathione peroxidase 1 (GPx1) and glutathione S-transferase theta 1 (GSTT1) mRNA expression levels in heat-stressed broilers (p < 0.05). Furthermore, compared with the HS group, broilers fed with an ADP supplemented diet had a higher relative mRNA expression of inhibitor kappa B alpha (IκBα) (p < 0.05) and a lower relative mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the duodenum (p < 0.05). In summary, dietary ADP supplementation had an ameliorative effect on HS-induced impairment of tight junctions, antioxidant capacity and the immune response of the duodenum in broilers. These beneficial effects might be related to the modulation of Nrf2 and NF-κB signaling pathways.

中文翻译：

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日粮添加海藻多糖对热应激下肉鸡十二指肠形态、紧密连接、抗氧化能力和免疫反应的影响

为了评估补充藻源多糖 (ADP) 对肉鸡热应激 (HS) 所致十二指肠损伤的改善作用，将 144 只雄性黄羽肉鸡（56 日龄）随机分为三组： TN组（中性区，肉鸡饲养在23.6±1.8°C）；HS组（热应激，肉鸡暴露于33.2±1.5°C 10 h/day，8:00 am-18:00 pm，其余时间温度与TN组一致）；HSA 组（热应激肉鸡饲喂 1000 mg/kg 的 ADP 补充日粮）。每个处理有 6 个重复，每个重复有 8 只肉鸡。喂养试验持续了四个星期。结果表明，日粮中添加 ADP 有增加绒毛高度的趋势（p= 0.077）和绒毛宽度（p = 0.062），并降低HS 下肉鸡十二指肠的细胞凋亡率（p = 0.081）。此外，日粮 ADP 增加了 HS 下肉鸡十二指肠中 occludin 和 zonula occludens-1 (ZO-1) 的相对 mRNA 和蛋白质（基于免疫荧光）表达水平（p < 0.05）。此外，日粮 ADP 增强了总抗氧化能力（T-AOC）和谷胱甘肽-S 转移酶（GST）的活性，同时降低了 HS 下肉鸡十二指肠的丙二醛（MDA）浓度（p < 0.05）。此外，膳食 ADP 补充剂上调了十二指肠核因子红系 2 相关因子 2 ( Nrf2 )、血红素加氧酶-1 ( HO-1))、谷胱甘肽过氧化物酶 1 ( GPx1 ) 和谷胱甘肽 S-转移酶 theta 1 ( GSTT1 ) 在热应激肉鸡中的 mRNA 表达水平 ( p < 0.05)。此外，与 HS 组相比，饲喂 ADP 补充日粮的肉鸡具有更高的抑制剂 kappa B α ( IκBα ) mRNA 表达( p < 0.05) 和更低的肿瘤坏死因子-α ( TNF-α ) mRNA 表达) 和十二指肠中的白细胞介素-1β ( IL-1β ) ( p< 0.05)。总之，日粮中添加 ADP 对 HS 诱导的肉鸡十二指肠紧密连接、抗氧化能力和免疫反应的损害具有改善作用。这些有益作用可能与 Nrf2 和 NF-κB 信号通路的调节有关。