Emodin Improved the Hepatic Metabolic Dysfunction Induced by High Plant‐Protein Diet in Pengze Crucian Carp ( Carassius auratus var. Pengze)

High plant‐protein (HP) diets could induce bile acid (BA) imbalance and lipid metabolism disorder in fish, and emodin supplementation has been reported to increase serum BA levels and improve lipid metabolism with a lack of understanding of its underlying mechanism. To explore this scientific problem, Pengze crucian carp were respectively fed with normal fishmeal (FM) diet, HP diet, and HP diet with different levels of emodin (25, 50, 75, and 100 mg/kg) for 8 weeks. The results revealed that appropriate emodin supplementation recovered intestinal BAs absorption function through the inhibition of intestinal inflammation and promoted the hepatic BAs synthesis by inhibiting farnesoid X receptor (FXR)‐FGF19‐CYP7A1 signaling pathway in carp fed with HP diet. Emodin exerted cholesterol (CHOL)‐lowering effects by inhibiting the excessive synthesis of CHOL induced by HP diet and promoting the transport of CHOL, and drived the conversion of CHOL to BAs in liver tissue. The increase in BA levels induced by emodin supplementation could suppress lipid lipogenesis and alleviate hepatic lipid deposition through the activation of AMP‐activated protein kinase (AMPK). In summary, dietary a suitable content of emodin could improve the metabolism of BA, CHOL, and lipid in liver tissue, and ultimately attenuate hepatic metabolic dysfunction of Pengze crucian carp induced by HP diet.