Effects of supplementing taurine in all‐plant protein diets on growth performance, serum parameters, and cholesterol 7α‐hydroxylase gene expression in black sea bream, <scp><i>Acanthopagrus schlegelii</i></scp>

Abstract

Taurine has been reported as an important nutrient in some fish species, but its efficacy in black sea bream, Acanthopagrus schlegelii has not been determined. Therefore, a study was performed to explore the effects of taurine supplementation on growth performance, serum parameters, and related gene expression in black sea bream juveniles fed all‐plant protein diets. A fishmeal diet (FM) and five all‐plant protein diets with graded taurine levels (T0, T0.25, T0.5, T1, and T2) were formulated. The results showed that all‐plant protein diets could significantly inhibit fish growth, but dietary taurine supplementation could significantly improve weight gain, thermal unit growth coefficient, feed efficiency, and protein retention efficiency when fish are fed with an all‐plant protein diet. No significant differences were observed in moisture, crude protein, and crude lipid content of the whole body and dorsal muscle among all treatments. Dietary taurine supplementation could significantly increase serum total protein and albumin but significantly decrease serum total cholesterol and hepatic total bile acid in all‐plant protein diets. Fish fed the T0 diet showed a significantly lower cholesterol 7α‐hydroxylase ( CYP7A1 ) messenger RNA (mRNA) level than the FM group, but dietary taurine supplementation could significantly improve CYP7A1 mRNA expression.