COMBINED EFFECTS OF DIETARY PHOSPHATIDYLCHOLINE AND CHOLESTEROL ON THE GROWTH, SURVIVAL AND BODY LIPID-COMPOSITION OF MARINE SHRIMP, PENAEUS-PENICILLATUS

A factorial experiment with four dietary phosphatidylcholine (0, 1.25, 2.5 and 5%) and three cholesterol (0, 0.5 and 1%) levels was carried out using juvenile Penaeus penicillatus with an initial mean body weight of 1 g. The trial was conducted for only 4 weeks using purified diets. The results indicated that diets supplemented with either phosphatidylcholine or cholesterol significantly improved shrimp weight gain. Supplementary cholesterol, but not phosphatidylcholine, significantly improved shrimp food conversion and survival. The interactions between phosphatidylcholine and cholesterol on shrimp growth, food conversion and survival were not significant. The dietary cholesterol level to achieve significant shrimp growth was 0.5% or higher, while that for phosphatidylcholine was 1.25% or higher. The inclusion of cholesterol in the purified diets affected lipid deposition. The shrimp muscle lipid content increased with the increased supplement of cholesterol or phosphatidylcholine. The lipid class composition, however, was not influenced by the two dietary components. Both the n3/n6 ratios of the fatty acids and the n3-PUFA level in the polar fraction of the muscle tissue lipid increased with reduced dietary phosphatidylcholine. The n6 fatty acids derived from the soy phosphatidylcholine were accumulated and preferentially incorporated into the polar lipid of the muscle tissue.