Conjugated Bile Acids Enhance Growth Performance, Liver Health, and Bile Acid Metabolism in Pearl Gentian Grouper Fed a High Plant‐Protein Diet

The conjugation states of bile acids (BAs) have been demonstrated to affect BAs regulatory functions. This study aimed to investigate the effects of conjugated or non‐conjugated BA additions on growth performance, liver health, and BA metabolism in pearl gentian grouper ( Epinephelus lanceolatus ♂ × E. fuscoguttatus ♀), as well as to elucidate the underlying mechanisms. The 300 healthy experimental fish, each with an average initial body weight (IBW) of 15.21 ± 0.04 g, were randomly distributed into 12 tanks (300 L per tank). The experiment consisted of four dietary groups, with three replicates per group: the control diet (CD) group, the plant protein‐based diet (PD) group, the PD supplemented with conjugated BAs (CBD) group, and the PD supplemented with non‐conjugated BA diet (NBD) group. The findings indicated that, in comparison to the CD group, the grouper fed a PD exhibited deleterious effects on growth performance, BA metabolism, and liver health. This was evidenced by increased levels of of oxidative stress, endoplasmic reticulum (ER) stress, apoptosis, and inflammatory response. In comparison to the PD group, the CBD treatment demonstrated favorable outcomes with respect to growth performance and liver health in the grouper. Additionally, it facilitated BA metabolism, as evidenced by enhanced BA transport, reabsorption, and recycling. Compared to PD group, the NBD treatment further impaired BA metabolism and induced cell apoptosis. Additionally, six metabolites, 3‐Dehydrocarnitine, Stizolobate, Bilastine, S‐(‐)‐Ureidoglycolate, 5,6‐Dihydroxyindole, and 4‐O‐methylnorbelladine‐, were identified as biomarkers among the treatment groups. Moreover, high plant‐protein replacement and BAs addition both impacted the pathways associated with the “Biosynthesis of various plant secondary metabolites“ and “Central carbon metabolism in cancer. “In conclusion, the conjugated BAs improve growth performance, liver health, and BA metabolism in pearl gentian grouper fed a high plant‐protein diet.