High-grain diet feeding alters ileal microbiota and disrupts bile acid metabolism in lactating dairy cows

文献类型： 外文期刊

第一作者： Lai, Zheng

作者： Lai, Zheng;Zhan, Xiaoxiu;Lin, Limei;Zhang, Jiyou;Qi, Weibiao;Yang, Huisheng;Mao, Shengyong;Jin, Wei;Lai, Zheng;Zhan, Xiaoxiu;Lin, Limei;Zhang, Jiyou;Qi, Weibiao;Yang, Huisheng;Mao, Shengyong;Jin, Wei;Jin, Wei

作者机构：

关键词： bile acid metabolism; dairy cows; FXR/FGF19; high-grain diet; ileal bacterial community

期刊名称：JOURNAL OF ANIMAL SCIENCE （ 影响因子：3.3； 五年影响因子：3.1 ）

ISSN： 0021-8812

年卷期： 2023 年 101 卷

页码：

收录情况： SCI

摘要： Bile acids (BAs) play an important role in the regulation of lipid metabolic homeostasis, but little is known about their metabolism in dairy cows fed a high-grain (HG) diet. In the present study, we examined the bacterial community, BA profile, and the FXR/FGF19 signaling pathway in the ileum and liver to investigate the gut microbe-BA metabolism interactions response to HG diet and the changes in the subsequent enterohepatic circulation of dairy cows. The results showed that the ileal bacterial community was altered, with an increase of Paraclostridium, Anaerobutyricum, Shuttleworthia, and Stomatobaculum in the relative abundance in the HG group. Moreover, real-time polymerase chain reaction (PCR) showed that the abundance of total bacteria and bacterial bile-salt hydrolase (BSH) genes was increased in the ileal digesta in the HG group. Meanwhile, HG feeding also decreased the total BA content in the digesta of jejunum and ileum and in feces. HG feeding altered the BA profile in the ileal digesta by increasing unconjugated BAs and decreasing conjugated BAs. In addition, the intestinal FXR/FGF19 signaling pathway was activated. The expression of CYP7A1 (cholesterol 7 & alpha;-hydroxylase) was depressed, which inhibited BAs synthesis in the liver of cows fed HG. Overall, HG feeding altered the ileal bacterial community and BA profile, and activated FXR/FGF19 signaling pathway, resulting in a decrease of BA level in the ileal digesta via the inhibition of hepatic BA synthesis. The findings provided novel insights into understanding the relationship between gut microbiota and the homeostasis of BAs in dairy cows fed a HG diet. High-grain diet altered the ileal bacterial community and bile acids metabolism, leading to the activation of FXR/FGF19 signaling pathway and the inhibition of hepatic bile acid synthesis, which finally decreased the total bile acid level in the digesta of ileum. Bile acids plays an important role in regulating lipids metabolism in animals and human. Dairy cows fed high-grain (HG) diet generally suffer abnormal lipids metabolism. However, if there is a relationship between the bile acids metabolism and abnormal lipids metabolism in dairy cows fed HG diet is unclear. This study found that HG diet altered the bacterial community and bile aids composition in the ileum of dairy cows. HG also activated the FXR/FGF19 signaling pathway in the ileum, and inhibited the bile acid synthesis in the liver, which might be the reason for the reduced level of bile acid in the digesta of small intestine. The reduced bile acid level in the small intestine might affect the digestion and absorption of the dietary lipids in dairy cows fed HG diet.

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