INFLUENCE OF PHOSPHOLIPID AND HIGHLY UNSATURATED FATTY-ACIDS ON SPAWNING RATE AND EGG AND TISSUE COMPOSITION IN PENAEUS-VANNAMEI FED SEMI-PURIFIED DIETS

In order to study the influence of dietary phospholipids (PL) and highly unsaturated fatty acids (HUFA) on spawning rate and egg and organ lipid composition of P. vannamei, three batches of eyestalk-ablated spawners were fed semi-purified diets for a period of 45 days. The semi-purified diets differed only in their lipid composition: diet HR had high HUFA and PL concentrations, diet PLD had low HUFA and high PL concentrations, while diet PLD had low PL and HUFA concentrations. Control spawners were fed fresh mussel. The spawning rate of the PLD group was one-third of that obtained in the other three groups. Egg numbers per spawning were similar in groups fed the semipurified diets but significantly inferior (P<0.05) to the number observed in the control group. A large lipid deposition, mainly due to neutral lipid (NL), was observed in the hepatopancreas of animals fed semi-purified diets. The total lipid concentration of eggs did not significantly change with the different diets, but PL concentration of eggs was affected by that of diet. Fatty acid composition of both PL and NL of hepatopancreas, muscle and eggs was widely affected by dietary fatty acid composition. The time course variation of egg fatty acid composition during the feeding period notably showed that the HUFA concentration in eggs of HD and PLD groups fell below 2.5% dry matter after 20 days while it was maintained at up to 4% in eggs of the control group. The ability of eggs containing such a low level of HUFA to sustain lecitotrophic development is discussed with reference to previous studies.