The effect of dietary lecithin and lipid levels on the growth performance, body composition, hemolymph parameters, immune responses, body texture, and gene expression of juvenile white shrimp (Litopenaeus vannamei)

Abstract

This study evaluated the effects of dietary soy lecithin and lipid levels on lipid utilization by white shrimp (Litopenaeus vannamei). Ten isonitrogenous experimental diets were formulated with three levels of lipid (7%, 9%, and 11%) and three levels of soy lecithin (0.6%, 1.2%, and 1.8%), and one diet with a 7% lipid level and without lecithin was the control diet; all the diets contained approximately 38.5% protein with 20% fish meal. A total of 600 shrimps (initial weight: 1.02 +/- 0.01 g) were randomly assigned to thirty 96-L glass tanks (10 dietary groups x 3 replicates) in a recirculation system for 8 weeks. The shrimps were fed to near satiation with three meals daily for 8 weeks. Regardless of lecithin levels, final biomass, biomass gain, whole-body and hepatopancreatic lipid concentrations, hemolymph triglyceride (TG), cholesterol concentrations, superoxide dismutase (SOD), muscle gumminess, chewiness, and cohesiveness values increased with increasing dietary lipid levels. Hemolymph glutathione peroxidase (GPx) and muscle hardness exhibited an increased trend with increment of dietary lipid and lecithin levels. The highest values of these parameters were observed in shrimp fed the diet with 11% lipid and 1.8% lecithin. Delta-6-desaturase (D-6) gene expression in the hepatopancreas of the white shrimp showed the best expression in diets containing 9% lipid and 1.8% lecithin. Hepatopancreatic GPx and lipase expression in the white shrimp fed the 1.8% lecithin diet was higher than those in shrimp fed diets with other lecithin levels. The results suggested that the white shrimp fed the diet with 11% lipid and 1.8% lecithin exhibited the optimal growth performance, hemolymph parameters, body texture, and immune responses.