College of Animal Science and Technology, Key Laboratory of Animal Origin Food Production and Safety Guarantee of Jiangsu Province, Jiangsu Collaborative Innovation Center of Meat Production and Processing, Quality and Safety Control, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.
Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, People's Republic of China.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skac355.
The current study is designed to investigate dietary guanidinoacetic acid (GAA) supplementation on the growth performance, intestinal histomorphology, and jejunum mucosal barrier function of broilers that are subjected to chronic heat stress (HS). A total of 192 male broilers (28-d old) were randomly allocated to four groups. A chronic HS model (at a temperature of 32 °C and 50%-60% relative humidity for 24 h daily) was applied in the experiment. Normal control (NC, ad libitum feeding, 22 °C), HS group (HS, ad libitum feeding, 32 °C), pair-fed group (PF, received food equivalent to that consumed by the HS group on the previous day, 22 °C), guanidinoacetic acid group (HG, ad libitum feeding, supplementing the basal diet with 0.6 g/kg GAA, 32 °C). The experiment lasted from 28 to 35 and 28 to 42 d of age of broilers. Our results showed that broilers subjected to HS had lower average daily feed intake and average daily gain (P < 0.05), higher feed-to-gain ratio and relative length of the small intestine (P < 0.05), as well as lower relative weight and weight per unit length of the small intestine (P < 0.05). HS damaged the small intestinal histomorphology by decreasing the small intestinal VH and the VH/CD (P < 0.05). Compared with the HS group, supplementation with 0.6 g/kg GAA increased jejunal VH and VH/CD (P < 0.05), but decreased relative weight and relative length of the small intestine (P < 0.05). Moreover, in comparison with NC, HS elevated intestinal permeability (D-Lactic acid concentration and diamine oxidase activity) and mRNA expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α (P < 0.05), reduced jejunal mucus thickness, number of goblet cells, IgA + cell density, and mucin2 mRNA expression level of broilers (P < 0.05). Compared with the HS group, dietary GAA elevated jejunal mucus thickness, goblet cell number and IgA+ cell density (P < 0.05), and up-regulated jejunal mRNA expression of interleukin-1β and tumor necrosis factor-α (P < 0.05). In conclusion, HS impaired growth performance, and the intestinal mucosal barrier function of broilers. Dietary supplementation with 0.6 g/kg GAA alleviated HS-induced histomorphology changes of small intestine and jejunal mucosal barrier dysfunction.
本研究旨在探讨日粮胍基乙酸（GAA）对遭受慢性热应激（HS）的肉鸡生长性能、肠道组织形态和空肠黏膜屏障功能的影响。将 192 只 28 日龄雄性肉鸡随机分为 4 组。实验采用慢性 HS 模型（温度为 32°C，相对湿度为 50%-60%，每天 24 h）。正常对照组（NC，自由采食，22°C）、HS 组（HS，自由采食，32°C）、等热量限饲组（PF，接受与前一天 HS 组相同的食物，22°C）、GAA 组（HG，自由采食，基础日粮中添加 0.6 g/kg GAA，32°C）。肉鸡的试验期为 28-35 日龄和 28-42 日龄。结果表明，HS 组肉鸡的平均日采食量和平均日增重降低（P<0.05），料重比和小肠相对长度增加（P<0.05），小肠相对重量和单位长度小肠重量降低（P<0.05）。HS 破坏了小肠组织形态，降低了空肠 VH 和 VH/CD（P<0.05）。与 HS 组相比，日粮添加 0.6 g/kg GAA 增加了空肠 VH 和 VH/CD（P<0.05），但降低了小肠的相对重量和相对长度（P<0.05）。此外，与 NC 相比，HS 组提高了肠道通透性（D-乳酸浓度和二胺氧化酶活性）和白细胞介素-1β、白细胞介素-6 和肿瘤坏死因子-α的 mRNA 表达水平（P<0.05），降低了肉鸡空肠黏液厚度、杯状细胞数量、IgA+细胞密度和黏蛋白 2 mRNA 表达水平（P<0.05）。与 HS 组相比，日粮 GAA 增加了空肠黏液厚度、杯状细胞数量和 IgA+细胞密度（P<0.05），并上调了空肠白细胞介素-1β和肿瘤坏死因子-α的 mRNA 表达水平（P<0.05）。综上所述，HS 降低了肉鸡的生长性能和肠道黏膜屏障功能，日粮添加 0.6 g/kg GAA 可缓解 HS 引起的小肠组织形态变化和空肠黏膜屏障功能障碍。
