THE IMPACT OF SEASONAL ALTERATION IN THE LIPID-COMPOSITION OF BROODSTOCK DIETS ON EGG QUALITY IN THE EUROPEAN SEA BASS

Groups of European sea bass Dicentrarchus labrax L., broodstock were f ed two pelleted, lipid-enriched diets [maize oil, low essential fatty acid (EFA) or fish oil, high EFA]. Those fed the high EFA diet for 12 months or only during vitellogenesis (September to February) with the low EFA diet fed for the remaining 6 months, showed improved egg quali ty and higher hatching rates when compared to two groups fed the high EFA diet during either previtellogenesis (February to September) or th e spawning period (February to April). The higher quality eggs contain ed higher levels of total n-3 fatty acids, including increased levels of both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Hi gh levels of triacylglycerol (TAG) were linked with the poorer quality eggs from those groups fed the low EFA diet during the period of vite llogenesis. The present work identifies vitellogenesis as the period i n the maturation during which EFA are incorporated most effectively in to the developing oocytes. (C) 1997 The Fisheries Society of the Briti sh Isles.