背景:已知高脂肪饮食(HFD)可以提高肉鸡的饲料转化率,然而,它们也会导致肝脏脂肪堆积。胆汁酸(BA)和肠道菌群在脂肪肝的形成中也起着关键作用。在这项研究中,我们的目的是阐明补充BA减少肉鸡肝脏脂肪沉积的机制,重点关注肠道微生物群和肝脏BA组成的参与。
结果:新孵化的肉鸡被分配到低脂饮食(LFD)或HFD,有或没有BA补充,随后评估了它们对肠道微生物群的影响,肝脏脂质代谢,和肝BA成分。结果表明,添加BA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成酶(FAS)的表达水平显著降低(P<0.05)。这些结果表明,补充BA可有效减少肝脏脂肪沉积。在LFD下,BAs的补充增加了肝脏中的BA含量和非12-OHBAs/12-OHBAs的比例,并增加了盲肠中的Akkermansia丰度。根据HFD,补充BA降低了BAs并增加了肝组织中鹅去氧胆酸(CDCA)和胆酸(CA)的相对丰度,而类杆菌的相对丰度急剧下降,双歧杆菌,埃希氏菌,盲肠中乳杆菌增多。相关分析表明,在LFD下,Akkermansia丰度与非12-OHBA含量呈显著正相关,在HFD下,拟杆菌丰度与CA或CDCA含量之间呈显着负相关。
结论:结果表明,在LFD和HFD中补充BA可能会改善肉鸡的肝脏脂肪沉积,并涉及分化的微生物群-胆汁酸谱途径。
BACKGROUND: 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.
RESULTS: 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.
CONCLUSIONS: 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.