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 high ly unsaturated fatty acids (HUFA) on spawning rate and egg and organ l ipid composition of P. vannamei, three batches of eyestalk-ablated spa wners were fed semi-purified diets for a period of 45 days. The semi-p urified diets differed only in their lipid composition: diet HR had hi gh HUFA and PL concentrations, diet PLD had low HUFA and high PL conce ntrations, 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 signif icantly inferior (P<0.05) to the number observed in the control group. A large lipid deposition, mainly due to neutral lipid (NL), was obser ved in the hepatopancreas of animals fed semi-purified diets. The tota l lipid concentration of eggs did not significantly change with the di fferent diets, but PL concentration of eggs was affected by that of di et. Fatty acid composition of both PL and NL of hepatopancreas, muscle and eggs was widely affected by dietary fatty acid composition. The t ime course variation of egg fatty acid composition during the feeding period notably showed that the HUFA concentration in eggs of HD and PL D groups fell below 2.5% dry matter after 20 days while it was maintai ned at up to 4% in eggs of the control group. The ability of eggs cont aining such a low level of HUFA to sustain lecitotrophic development i s discussed with reference to previous studies.