Comparative study on the effect of high dietary carbohydrate on the growth performance, body composition, serum physiological responses and hepatic antioxidant abilities in Wuchang bream (Megalobrama amblycephala) and black carp (Mylopharyngodon piceus Ri

Abstract

A 90-day trial investigated the effect of dietary carbohydrate level on growth performance, body composition, serum physiological responses and hepatic antioxidant abilities of a herbivorous fish, Wuchang bream (Megalobrama amblycephala) and a carnivorous fish, black carp (Mylopharyngodon piceus Richardson, 1846). For each species, two isonitrogenous and isolipidic semi-purified diets (28.6% crude protein and 5.3% crude lipid for Wuchang bream) were formulated to contain 30.4% and 52.9% carbohydrate (WB-NCHO and WB-HCHO); Two isonitrogenous and isolipidic semi-purified diets (32.6% crude protein and 5.3% crude lipid for black carp) were formulated to contain 20.5% and 40.5% carbohydrate (BC-NCHO and BC-HCHO). It was shown that, compared to Group WB-NCHO, Wuchang bream in Group WB-HCHO had lower weight gain rate, specific growth rate, serum total protein, hepatic superoxide dismutase activity and total antioxidative capacity, while higher feed conversion ratio, serum triglyceride and cortisol levels (P < 0.05). Compared to Group BC-NCHO, black carp in Group BC-HCHO had lower final weight, weight gain rate, specific growth rate, protein efficiency ratio, serum alkaline alkaline phosphatase activity, serum total protein, hepatic superoxide dismutase activity and total antioxidative capacity, while higher feed conversion ratio, whole body crude lipid, serum triglyceride, cholesterol, glutamic-oxaloacetic transaminase activity and cortisol levels (P < 0.05). The results of this study suggested that Wuchang bream had better capacity of utilizing dietary carbohydrate than that of black carp, while high levels of dietary carbohydrate might not only be detrimental to growth performance and feed utilization but also the immune response and health for both species.