High-fat diets (HFD) are known to enhance feed conversion ratio in broiler chickens, yet they can also result in hepatic fat accumulation. Bile acids (BAs) and gut microbiota also play key roles in the formation of fatty liver. In this study, our objective was to elucidate the mechanisms through which BA supplementation reduces hepatic fat deposition in broiler chickens, with a focus on the involvement of gut microbiota and liver BA composition. Newly hatched broiler chickens were allocated to either a low-fat diet (LFD) or HFD, supplemented with or without BAs, and subsequently assessed their impacts on gut microbiota, hepatic lipid metabolism, and hepatic BA composition. Our findings showed that BA supplementation significantly reduced plasma and liver tissue triglyceride (TG) levels in 42-day-old broiler chickens (P < 0.05), concurrently with a significant decrease in the expression levels of fatty acid synthase (FAS) in liver tissue (P < 0.05). These results suggest that BA supplementation effectively diminishes hepatic fat deposition. Under the LFD, BAs supplementation increased the BA content and ratio of Non 12-OH BAs/12-OH BAs in the liver and increased the Akkermansia abundance in cecum. Under the HFD, BA supplementation decreased the BAs and increased the relative abundances of chenodeoxycholic acid (CDCA) and cholic acid (CA) in hepatic tissue, while the relative abundances of Bacteroides were dramatically reduced and the Bifidobacterium, Escherichia, and Lactobacillus were increased in cecum. Correlation analyses showed a significant positive correlation between the Akkermansia abundance and Non 12-OH BA content under the LFD, and presented a significant negative correlation between the Bacteroides abundance and CA or CDCA content under the HFD. The results indicate that supplementation of BAs in both LFD and HFD may ameliorate hepatic fat deposition in broiler chickens with the involvement of differentiated microbiota–bile acid profile pathways.

中文翻译：

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日粮胆汁酸补充剂可减少肉鸡肠道微生物群和肝脏胆汁酸谱改变的肝脏脂肪沉积


众所周知，高脂饮食 （HFD） 可以提高肉鸡的饲料转化率，但它们也会导致肝脏脂肪堆积。胆汁酸 （BAs） 和肠道微生物群在脂肪肝的形成中也起着关键作用。在这项研究中，我们的目标是阐明补充 BA 减少肉鸡肝脏脂肪沉积的机制，重点是肠道微生物群和肝脏 BA 组成的参与。将新孵化的肉鸡分配到低脂饮食 （LFD） 或 HFD 组，补充或不补充 BAs，随后评估它们对肠道菌群、肝脏脂质代谢和肝脏 BA 组成的影响。研究结果显示，补充 BA 可显著降低 42 日龄肉鸡血浆和肝组织甘油三酯 （TG） 水平 （P < 0.05），同时肝组织中脂肪酸合酶 （FAS） 表达水平显著降低 （P < 0.05）。这些结果表明，BA 补充剂可有效减少肝脏脂肪沉积。在 LFD 下，补充 BAs 增加了肝脏中非 12-OH BAs/12-OH BAs 的 BA 含量和比例，并增加了盲肠中 Akkermansia 的丰度。在 HFD 下，BA 补充剂降低了 BAs，增加了肝组织中鹅去氧胆酸 （CDCA） 和胆酸 （CA） 的相对丰度，而拟杆菌的相对丰度显著降低，盲肠中的双歧杆菌、埃希氏菌属和乳酸杆菌属增加。相关性分析显示，LFD 下 Akkermansia 丰度与 Non 12-OH BA 含量呈显著正相关，HFD 下拟杆菌属丰度与 CA 或 CDCA 含量呈显著负相关。 结果表明，在 LFD 和 HFD 中补充 BAs 可能会改善肉鸡的肝脏脂肪沉积，涉及分化的微生物群-胆汁酸谱途径。