Characterization of the cpt1b Gene in Response to a Tributyrin-Supplemented Diet: Cloning, Tissue-Specific Expression, and Intestinal Metabolic Function in Mandarin Fish (Siniperca chuatsi)

Tributyrin (TB), as a novel feed additive, holds broad market prospects and is crucial for promoting fish growth and maintaining intestinal health. We first identified the fatty acid metabolism-related gene <i>cpt1b</i> in the intestines of mandarin fish (<i>Siniperca chuatsi</i>) from the TB-supplemented group. A total of 600 mandarin fish (200.0 ± 5.0 g) were evenly allocated into three groups. The control group (C) received only the standard extruded feed, while the experimental groups were supplemented with tributyrin (TB) at concentrations of 500 mg/kg (T1 group) and 1000 mg/kg (T2 group), respectively. Cloning yielded a 2364 bp open reading frame (ORF) encoding 787 amino acids, with the gene possessing two conserved transmembrane domains. Phylogenetic analysis further indicated a close phylogenetic relationship between largemouth blackbass (<i>Micropterus salmoides</i>) and mandarin fish. Tissue distribution and intestinal enzyme activity analyses revealed that supplementation with varying concentrations of TB upregulates <i>cpt1b</i> gene expression in different tissues, while modulating intestinal digestive enzyme and antioxidant enzyme activities. Our findings suggest a potential mechanism involving enhanced intestinal enzyme activity, reduced fat accumulation, increased expression of lipid oxidation-related genes, and accelerated TB degradation in the intestine.