Effects of dietary protein and lipid levels on growth and energy productive value of pacific white shrimp, Litopenaeus vannamei, at different salinities

A 8-week feeding experiment was conducted to evaluate the effect of different dietary protein and lipid levels on growth and energy productive value of juvenile Litopenaeus vannamei, at 30 and 2 ppt, respectively. Nine practical diets were formulated to contain three protein levels (380, 410 and 440 g kg-1) and three lipid levels (60, 80 and 100 g kg-1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The effects of salinity and an interaction between dietary protein level and lipid level on growth and energy productive value of shrimp were observed under the experimental conditions of this study. At 30 ppt seawater, shrimp fed with 440 g kg-1protein diets had significantly higher weight gain (WG) than those fed with 380 g kg-1 protein diets at the same dietary lipid level, and the 60 g kg-1 lipid group showed higher growth than 80 g kg-1and 100 g kg-1 lipid groups at the same dietary protein level. At 2 ppt seawater, the growth of shrimp was little affected by dietary protein treatments when shrimp fed the 80 and 100 g kg-1 lipid, shrimp fed the 80 g kg-1 lipid diets had only slightly higher growth than that fed 60and 100 g kg-1 lipid diets when fed 380 and 410 g kg-1 dietary protein diets. A significant effect of salinity on growth of shrimp was detected with the growth responses at 30 ppt > 2ppt (P < 0.05). Final body lipid content, body protein content and energy productive value of shrimp was significantly higher in animals exposed to 30 ppt than in shrimp held at 2 ppt.