Effects of Dietary Lipid and Carbohydrate and Their Interaction on Growth Performance and Body Composition of Juvenile Blunt Snout bream, Megalobrama amblycephala

The effects of dietary lipid and carbohydrate, and their interaction, on growth performance and body composition of juvenileblunt snout bream Megalobrama amblycephala were investigated. Fish were fed one of eight isonitrogenous (32% crude protein) diets containing 4% or 7% lipids and 25%, 30%, 35%, or 40% carbohydrate for nine weeks. Weight gain, feed conversion ratio, protein efficiency ratio, and nitrogen and energy retention improved significantly as the dietary lipid level increased, while there were no significant differences in these parameters within the tested range of carbohydrate levels. The interaction between the lipid and carbohydrate levels had positive effects on weight gain, feed conversion ratio, and protein efficiency ratio when fish were fed increased carbohydrates and 7% lipid. The intraperitoneal fat ratio and liver lipid content were significantly affected by the dietary carbohydrate level and reached maximum values in fish fed 40% and 30% carbohydrates, respectively. Further, the dietary lipid and carbohydrate levels significantly affected body moisture and lipid content while there were no significant differences in body protein, ash, energy, or muscle and liver glycogen contents. Results indicate that the optimal dietary carbohydrate content for juvenile M. amblycephala is approximately 30% when dietary lipid is 4%. However, juvenile M. amblycephala can efficiently utilize 40% dietary carbohydrate with a dietary lipid content of 7%