Effects of five compound attractants in high plant‐based diets on feed intake and growth performance of juvenile turbot ( Scophthalmus maximus L . )

Abstract

An experiment was conducted to evaluate the effects of five attractants on feed intake, growth performance and appetite-regulating genes expression for juvenile turbot (Scophthalmus maximus L.). Fish were fed with seven diets: fish-meal-based diet (FM), fermented soybean meal replacing 45% fish meal (FSBM) and other diets with 1% compound attractant A (CA-A) consisting of amino acids, compound attractant B (CA-B) consisting of quaternary ammonium bases, compound attractant C (CA-C) consisting of nucleotides, compound attractant G (CA-G) consisting of the combination of CA-A, CA-B and CA-C and blue mussel protein hydrolysate (BMH) on the basis of FSBM diet respectively. Daily feed intake in CA-A group was significantly higher, but that in CA-B group was significantly lower than FSBM group. Similarly, specific growth rate was significantly enhanced in CA-A and CA-G groups and were significantly decreased in CA-B group. Protein efficiency ratio and protein retention in CA-B group were significantly lower than FSBM group. Furthermore, BMH supplement increased the mRNA expression of Ghrelin in the intestine of fish. These results showed that CA-A and CA-G supplement could enhance growth in plant-based diets, but CA-B supplement had the opposite effect, which might be associated with lower feed intake and lower feed utilization.