EFFECTS OF DIETARY DOCOSAHEXAENOIC ACID (DHA 22/6N-3) ON LIPID AND FATTY-ACID COMPOSITIONS AND GROWTH IN GILTHEAD SEA BREAM (SPARUS-AURATA L) LARVAE DURING 1ST FEEDING

The effects of dietary DHA levels on lipid class compositions, total lipid and phosphoglyceride fatty acid compositions and growth were investigated in gilthead sea bream, Sparus aurata, larvae during the first 2 weeks after hatching. Different dietary levels of DHA were supplied to the larvae in the rotifer, Brachionus plicatilis, previously enriched with (a) Nannochloropsis gaditana, (b) a mixture of N. gaditana, Isochrysis galbana and Rhodomonas sp. or, (c) Protein Selco (Artemia Systems). The results showed that growth performance of gilthead sea bream larvae at first feeding was influenced by both total n-3HUFA and DHA contents of the diet, the best growth rate being achieved with a high n-3HUFA content and a high DHA: EPA ratio. Lipid contents, nutritional status, and total lipid and phosphoglyceride DHA levels of the larvae were directly correlated with dietary DHA levels. The fatty acid compositional data suggested that dietary EPA could not contribute significantly to tissue DHA levels in larval gilthead sea bream, presumably due to low DELTA4 desaturase activity.