Effects of inositol on growth and metabolism for juvenile Litopenaeus vannamei at different salinities

To study the effects of inositol on the growth, serum biochemical indices, and non-specific immunity of juvenile Litopenaeus vannamei at different salinities (4 and 28), we fed the shrimps of the initial body mass of (0.75±0.00) g with six diets containing 0, 100, 200, 400, 800 and 1 600 mg∙kg⁻¹ inositol for 10 weeks, respectively. The results show that the final body mass, weight gain rate, survival rate, specific growth rate, protein efficiency, net protein utilization, total cholesterol, acid phosphatase, alkaline phosphatase, total superoxide dismutase and nitric oxide synthase were significantly higher at high salinity than at low salinity (P<0.05); while the feed coefficient and moisture were the reverse. The feed coefficient and total cholesterol content decreased with increasing inositol levels in the diet, but the final body mass, weight gain rate, survival rate, specific growth rate, protein efficiency and net protein utilization increased, and the hepatopancreas somatic indices, acid phosphatase and alkaline phosphatase were significantly higher in inositol-added groups than in the control group (P<0.05). In summary, feeding inositol diets are recommended to improve shrimp's growth, survival and immutability; shrimp's growth and immunity are suppressed at low salinity; feeding higher than 100 mg∙kg⁻¹ inositol diets can restore the growth to a high salinity level, and feeding higher than 200 mg∙kg⁻¹ inositol diets can improve shrimp's immunity.