Comparison of native, lyso and hydrogenated soybean phosphatidylcholine asphospholipid source in the diet of postlarval Penaeus japonicus bate

Native and two modified forms of soybean phosphatidylcholine were used to s tudy the nutritional effect of their fatty acids for postlarval Penaeus jap onicus. Five semipurified and isolipidic diets were formulated using casein as a protein source. Three diets contained 1.5 % of different types of pho sphatidylcholine (95 % purity), i.e. native soybean phosphatidylcholine, hy drogenated soybean phosphatidylcholine and 1-acyl lyse soybean phosphatidyl choline, besides 1% of n-3 highly unsaturated fatty acid formulated as trig lycerides. Two negative control diets contained either triglycerides or eth yl esters as a source of n-3 highly unsaturated fatty acids without phospho lipid. The experiment was conducted during two successive phases of 20 d st arting from 12-d old postlarvae. Feeding the diet containing native soybean phosphatidylcholine resulted in significantly better growth and resistance to osmotic shock of P. japonicus postlarvae compared to the other diets. T he total lipid content of the tissue was significantly increased by the sup plementation of soybean phosphatidylcholine, whereas no significant differe nce was observed for the shrimp fed the modified phosphatidylcholine source s compared to the phosphatidylcholine-free diet at the end of the experimen t. Shrimp fed the diet containing soybean phosphatidylcholine exhibited a h igher polar lipid fraction in the whole body total lipid mainly as a result of the increased proportion of phosphatidylcholine and to a lesser extent of phosphatidylinositol at the expense of free fatty acids, free sterols an d sterol esters. The content of 20 :5n-3, 22:6n-3 and total n-3 highly unsa turated fatty acids in the shrimp tissue were higher in shrimp fed the nati ve soybean and hydrogenated soybean phosphatidylcholine diets compared to t hose fed the phosphatidylcholine-free and I-acyl lyse soybean phosphatidylc holine-based diets. The fatty acid profile of tissue phosphatidylethanolami ne was more influenced by the type of dietary phosphatidylcholine than that of tissue phosphatidylcholine. In the absence of phospholipids in the diet , triglyceride fish oil and a mixture of ethyl ester concentrate and coconu t oil with similar n-3 highly unsaturated fatty acids content were equivale nt sources of n-3 highly unsaturated fatty acids. The beneficial effects of dietary phospholipids may be due to a more efficient transport and utiliza tion of dietary neutral lipids through a better lipid mobilization followin g absorption in the intestinal mucosa rather than due to a better emulsific ation of neutral lipid in the gut lumen. The functionality of phosphatidylc holine in the diet of postlarval P. japonicus requires the presence of unsa turated fatty acids and an intact fatty acid moiety.