Influence of dietary biotin levels on growth and non-specific immune response in large yellow croaker,Larimichthys croceaR

A 9-week feeding experiment was conducted to determine the effect of dietary biotin levels on growth performance and non-specific immune response of large yellow croaker. Fish (6.16 ± 0.09 g) were fed twice daily to apparent satiation with diets containing 0.00 (as the basal diet), 0.01, 0.05, 0.25, 1.24 and 6.22 mg biotin kg−1 diet. Results showed that fish fed the basal diet had the lowest survival rate, and fish fed 0.05 mg kg−1 dietary biotin achieved significantly higher final weight and weight gain. Dietary biotin levels had no significant influence on carcass crude lipid, moisture and ash content, but significantly influenced the carcass crude protein. Liver biotin concentration significantly increased with the supplementation of biotin, but no tissue saturation was found within the supplementation scope of biotin. Broken-line regression analysis of weight gain showed that juvenile large yellow croaker requires a minimum dietary biotin of 0.039 mg kg−1 for maximal growth. The analyses of serum parameters showed that the moderate- (0.05 mg kg−1) and high-dose (6.22 mg kg−1) dietary biotin significantly improved both lysozyme and alternative complement pathway activities, indicating dietary biotin within a certain range could improve the non-specific immune response of large yellow croaker.