Effect of lipid and n-3 HUFA levels in microdiets on growth, survival and fatty acid composition of larval gilthead seabream (Sparus aurata)

Abstract

The results of studies on the essential fatty acid requirement of larval gilthead seabream differ in the recommended n−3 HUFA levels in rotifers (Brachionus plicatilis) necessary to obtain optimal larval growth and survival. Some authors have suggested that the total lipid content of the rotifers may influence the fatty acid requirement of the larvae. In order to study this hypothesis, an experiment was conducted by feeding gilthead seabream larvae microdiets containing combinations of two lipid and two essential fatty acid levels. Fifteen-day-old gilthead seabream larvae were fed with 4 microparticulated diets containing the following lipid and n−3 HUFA levels: (A) 12.44% and 0.82%; (B) 12.72% and 2.16%; (C) 19.45% and 0.74%; and (D) 20.03% and 2.05%. Larvae were fed the experimental diets together with a small amount of rotifers cultured on baker's yeast for 12 days. Larvae fed Diet A had the lowest growth rate (P<0.05). There was no significant difference in size among the other treatments. Diets rich in n−3 HUFA (B and D) supported the best survival rates regardless of their lipid content. These results showed that for the lipid levels tested, the larval n−3 HUFA requirement did not decrease as the lipid level in the diet decreased.