Influence of dietary lipid composition on yolk protein components in sea bass, Dicentrarchus labrax

Abstract

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 September 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 groups were fed with a low EFA diet. The percentage of egg viability and the hatching rates were observed in every group. The two major yolk proteins, lipovitellin (LV) and phosvitin (PV), were isolated from the ovary and their changes were studied by SDS-gel electrophoresis. In fish fed the diet enriched with EFA only for two months (group B) a decrease was observed of the 8 kDa PV components associated with a diminished egg viability and hatching. However, no modification of vitellogenin (VTG) plasma levels and no improvement in fish growth were observed under the dietary conditions used.