Effect of dietary phospholipid on requirements for and incorporation of n − 3 highly unsaturated fatty acids in postlarval Penaeus japonicus Bate

Abstract

Penaeus japonicus postlarvae were fed three dietary levels of n − 3 highly unsaturated fatty acids (HUFA) (0, 0.5 and 1%) with or without 1.5% soybean phosphatidylcholine (SPC; 95% purity). The experiment was conducted during two successive phases of 20 days starting with 12-day-old postlarvae. Supplying 1.5% of SPC and 1% n − 3 HUFA in the diet significantly improved the growth, survival and resistance to osmotic stress of postlarvae compared to those fed phosphatidylcholine (PC)-free and HUFA-free diets, respectively. A significant interaction between dietary SPC and n − 3 HUFA was only found for their effect on resistance to osmotic stress. A significant drop in stress sensitivity was obtained in the PC-deprived shrimp only when 1% n − 3 HUFA were present in the diet, whereas the shrimp fed SPC exhibited a drop of stress sensitivity already at a level of 0.5% n − 3 HUFA. Increasing the dietary levels of n − 3 HUFA resulted in increased concentrations in the shrimp tissue of total body lipid content, 20:5 n − 3 and 22:6 n − 3; and reduced levels of 18:2 n − 6 and total n − 6 polyunsaturated fatty acids. Also, the proportion of 20:5 n − 3, 22:6 n − 3 and total n − 3 HUFA significantly increased in the two major shrimp phospholipids, PC and phosphatidylethanolamine (PE), with increasing level of dietary n − 3 HUFA. The changes in whole body total lipid, lipid composition and fatty acid composition of total lipid, PC and PE due to the addition of soybean phospholipid depended on the dietary level of n − 3 HUFA.