College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Feb;30(7):18026-18038. doi: 10.1007/s11356-022-23385-y. Epub 2022 Oct 7.
This study investigated the effects of synbiotics supplementation on growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress. One hundred and forty-four 22-day-old male broilers were randomly assigned to one of three treatment groups of six replicates each for a 21-day study, with eight birds per replicate. Broilers in the control group were reared at a thermoneutral temperature and received a basal diet. Broilers in the other two heat-stressed groups were fed a basal diet supplemented without (heat-stressed group) and with 1.5 g/kg synbiotic (synbiotic group). One and a half gram of the synbiotic consisted with 3 × 10 colony forming units (CFU) Clostridium butyricum, 1.5 × 10 CFU Bacillus licheniformis, 4.5 × 10 CFU Bacillus subtilis, 600 mg yeast cell wall, and 150 mg xylooligosaccharide. Compared with the control group, heat stress increased rectal temperatures at 28, 35, and 42 days of age, respectively (P < 0.05). Birds subjected to heat stress had reduced weight gain, feed intake, and feed efficiency during 22 to 42 days (P < 0.05). In contrast, supplementation with the synbiotic decreased rectal temperature at 42 days of age and elevated weight gain of heat stress-challenged broilers (P < 0.05). Heat-stressed broilers exhibited a lower superoxide dismutase (SOD) activity in jejunal mucosa and a higher malondialdehyde accumulation in serum, liver and jejunal mucosa (P < 0.05), and the regressive SOD activity was normalized to control level when supplementing synbiotic (P < 0.05). Heat stress increased interleukin-1β (IL-1β) and interferon-γ (IFN-γ) levels in serum and IL-1β content in jejunal mucosa of broilers (P < 0.05). Synbiotic reduced IL-1β level in serum of broilers subjected to heat stress (P < 0.05). Compared with the control group, elevated serum diamine oxidase activity and reduced jejunal villus height were observed in broilers of the heat-stressed group (P < 0.05), and the values of these two parameters in the synbiotic group were intermediate (P > 0.05). Heat stress upregulated mRNA abundance of IL-1β and IFN-γ and downregulated gene expression levels of occluding and zonula occluden-1 (ZO-1) in jejunal mucosa of broilers (P < 0.05). The alterations in the mRNA expression levels of jejunal IL-1β and ZO-1 were reversed by the synbiotic (P > 0.05). In conclusion, dietary synbiotics could improve growth performance, antioxidant capacity, immune function, and intestinal barrier function in heat-stressed broilers.
本研究旨在探讨合生元补充剂对遭受周期性热应激的肉鸡生长性能、抗氧化状态、免疫功能和肠道屏障功能的影响。将 144 只 22 日龄雄性肉鸡随机分为 3 个处理组，每个处理组 6 个重复，每个重复 8 只鸡，进行为期 21 天的试验。对照组在适温下饲养，接受基础日粮。另外两组热应激组在基础日粮中添加（热应激组）和不添加（合生元组）1.5 g/kg 合生元。合生元由 3×10 菌落形成单位（CFU）丁酸梭菌、1.5×10 CFU 地衣芽孢杆菌、4.5×10 CFU 枯草芽孢杆菌、600 mg 酵母细胞壁和 150 mg 木寡糖组成。与对照组相比，热应激分别使 28、35 和 42 日龄肉鸡直肠温度升高（P<0.05）。热应激鸡的 22 至 42 日龄体重增重、采食量和饲料效率降低（P<0.05）。相反，合生元的补充降低了 42 日龄肉鸡的直肠温度，并提高了热应激肉鸡的体重增重（P<0.05）。热应激鸡空肠黏膜中超氧化物歧化酶（SOD）活性降低，血清、肝脏和空肠黏膜丙二醛积累增加（P<0.05），补充合生元可使 SOD 活性恢复到对照组水平（P<0.05）。热应激增加了血清中白细胞介素-1β（IL-1β）和干扰素-γ（IFN-γ）水平以及空肠黏膜中 IL-1β 的含量（P<0.05），而合生元组的 IL-1β 水平降低（P<0.05）。与对照组相比，热应激组肉鸡血清中二胺氧化酶活性升高，空肠绒毛高度降低（P<0.05），而合生元组这两个参数的值处于中间（P>0.05）。热应激上调了肉鸡空肠黏膜中 IL-1β 和 IFN-γ 的 mRNA 丰度，并下调了 occluding 和 zonula occluden-1（ZO-1）的基因表达水平（P<0.05）。合生元可逆转空肠 IL-1β 和 ZO-1 的 mRNA 表达水平的变化（P>0.05）。综上所述，日粮合生元可改善热应激肉鸡的生长性能、抗氧化能力、免疫功能和肠道屏障功能。
