Evaluation of Schizochytrium meal in microdiets of Pacific white shrimp ( Litopenaeus vannamei ) larvae

A feeding trial was conducted to assess the effects of dietary Schizochytrium meal supplementation on survival, growth performance, activities of digestive enzymes and fatty acid composition in Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Four isonitrogenous and isolipidic diets were formulated to contain graded levels of Schizochytrium meal: 0% (S0, the control diet), 2% (S2), 4% (S4) and 6% dry matter (S6). Results showed that there was no significant difference in survival of shrimps among dietary treatments (P > 0.05). Shrimps fed diets with 2% and 4% microalgae meal had significantly higher specific growth rate (SGR) than that of shrimps fed diets with 0% and 6% microalgae meal, and no significant differences were observed between shrimps fed diets with 2% and 4% microalgae meal (P > 0.05). Activity of trypsin in the pancreatic and intestinal segments, and activity of amylase in the pancreatic segments were not significantly affected by dietary microalgae meal levels (P > 0.05). Specific activities of both alkaline phosphatase and leucine-aminopeptidase in intestine and purified brush border membrane of intestine were significantly higher in shrimps fed diet with 2% microalgae meal (P < 0.05). There were no significant differences in C18:2n-6, n-3 fatty acids, n-6fatty acids, PUFA and n-3/n-6 in muscle samples among dietary treatments. C16:1n-7, C18:1n-9, MUFA, C18:3n-3 and C20:5n-3 decreased, however, C20:4n-6 increased in the muscle as dietary microalgae meal level increased. In conclusion, 4% Schizochytrium meal in microdiets of shrimps can improve growth performance and may be a valuable additive in the microdiets of shrimps.