INFLUENCE OF DIETARY-LIPID COMPOSITION ON YOLK PROTEIN-COMPONENTS IN SEA BASS, DICENTRARCHUS-LABRAX

The influence of diet on yolk protein composition and egg survival was studied using the sea bass, Dicentrarchus labrax, as an experimental model. Females were fed to satiation with a high essential fatty acid (EFA) diet during four different periods in the annual cycle: from Sep tember to February (vitellogenesis, Group A), from February to April ( spawning, Group B), from April to September (postvitellogenesis, Group C) and all the year round (Group D). During the remaining months grou ps were fed with a low EFA diet. The percentage of egg viability and t he hatching rates were observed in every group. The two major yolk pro teins, lipovitellin (LV) and phosvitin (PV), were isolated from the ov ary and their changes were studied by SDS-gel electrophoresis. In fish fed the diet enriched with EFA only for two months (group B) a decrea se was observed of the 8 kDa PV components associated with a diminishe d egg viability and hatching. However, no modification of vitellogenin (VTG) plasma levels and no improvement in fish growth were observed u nder the dietary conditions used.