FATTY-ACIDS AND EGG QUALITY IN GREAT SCALLOP

Spawners of the great scallop, Pecten maximus, were conditioned on thr ee microalgal diets: T-Isochuysis, a mixture of four species (PTSC) an d Chaetoceros calcitrans. The polyunsaturated fatty acid (PUFA) compos ition of neutral and polar lipids of eggs was related to the fatty aci d composition of the diet. However, the 20 and 22 carbon PUFAs were ma intained at significant levels independent of those of the diet when t hese fatty acids were present in the diet at low levels. This effect w as more pronounced in the polar than in the neutral lipids. A preferen tial incorporation of 22:6(omega-3) and 20:4(omega-6) was demonstrated in the polar lipids. This emphasizes their role in ovogenesis and emb ryogenesis. The 22:6(omega-3) requirement of FI maximus was better sat isfied by T-Isochrysis, which favoured the highest incorporation of th is essential fatty acid in the eggs. The good success in reproduction obtained with this monospecies diet led us to modify multispecies diet s by increasing the level of 22:6(omega-3).