Effects of dietary phospholipids, cholesterol and choline chloride on growth, survival and tissue lipid fractions of Litopenaeus vannamei juveniles

Phospholipids and cholesterol are essential lipids for shrimp; yet, their nutritional relationships and effects on lipid metabolism are not well understood. Therefore, requirements for dietary phospholipids (PL), phosphatidylcholine (PC), cholesterol and choline chloride (CC) by Litopenaeus vannamei juveniles, and their nutritional relationships were evaluated under controlled conditions using semipurified diets in five separate studies.;In one study consisting of two separate feeding trials, dietary PL strongly interacted with cholesterol for enhancing shrimp growth. Dietary cholesterol requirements of L. vannamei were determined to be 0.35%, 0.14%, 0.13%, or 0.05% of diet when dietary PL were 0%, 1.5%, 3%, or 5% of diet, respectively. Optimal concentration of PL for shrimp growth was 5% of diet without cholesterol supplementation, and decreased to 3% when the diet was supplemented with cholesterol at 0.4%. Interaction between dietary PL and cholesterol also affected total lipid and triglyceride concentrations in the hepatopancreas, and cholesterol concentration in the muscle.;In another study consisting of two separate feeding trials, three different types of commercial soybean lecithin were in diets without cholesterol supplementation. Shrimp growth was significantly enhanced with incremental levels of PL from 0 to 4% of diet regardless of lecithin type.;In two other feeding trials, purified PC without or with 0.1% dietary cholesterol had no influence on shrimp growth. However, other PL (mainly phosphatidylethanolamine and phosphatidylinositol) showed significant growth-enhancing effects. Lipid concentration, free fatty acids and other PL of shrimp hepatopancreas decreased with incremental increases in dietary PC concentration.;A final feeding trial investigated the effect of dietary PL on the CC requirement of shrimp. Based on instantaneous growth rate, the minimum CC requirement was estimated to be approximately 1000 mg/kg diet without dietary PL. No choline deficiency was observed when PL were included in the diets at 1.5% or 3%; however, CC could not substitute for PL in the diet. Triglycerides, free fatty acids, and cholesterol in shrimp muscle were affected by the interaction between dietary CC and PL.;These studies provide insights concerning lipid nutrition of shrimp and may be used in refining diet formulations for intensive culture of L. vannamei.