Fatty acids and egg quality in great scallop

Spawners of the great scallop, Pecten moximus, were conditioned on three microalgal diets: T-Isochrysis, a mixture of four species (PTSC) and Chaetoceros calcitrans.The polyunsaturated fatty acid (PUFA) composition of neutral and polar lipids of eggs was related to the fatty acid composition of the diet. However, the 20 and 22 carbon PUFAs were maintained at significant levels independent of those of the diet when these fatty acids were present in the diet at low levels. This effect was more pronounced in the polar than in the neutral lipids. A preferential incorporation of 22:6(-3) and 20:4(-6) was demonstrated in the polar lipids. This emphasizes their role in ovogenesis and embryogenesis.The 22:6(-3) requirement of P. maximus was better satisfied by T-Isochrysis, which favoured the highest incorporation of this essential fatty acid in the eggs. The good success in reproduction obtained with this monospecies diet led us to modify multispecies diets by increasing the level of 22:6(-3).