A standard experimental diet for the study of fatty acid requirements of weaning and first ongrowing stages of the European sea bass Dicentrarchus labrax L: Comparison of extruded and extruded/coated diets

The stability of the coated lipid fraction of a standard weaning diet was verified by comparing growth and fatty acid incorporation for European sea bass fed diets with an identical formulation but prepared either by extrusion/coating or extrusion only. For each type of experimental diet, a (n-3) HUFA level of 1 and 2.5% of the dry diet was evaluated. European sea bass Dicentrarchus labrax L. were weaned and consequently reared for 23 days on the experimental diets in a recirculation system. A commercial weaning diet served asa control. Final individual dry weight of sea bass larvae weaned and ongrown for a total period of 30 days on the various diets did not differ significantly. The (n-3) HUFA content of the fish tissue was a reflection of the dietary (n-3) HUFA content and was not influenced by the technique used to include the essential fatty acids in the diet. The (n-3) HUFA requirements of European sea bass during and immediately after weaning did not exceed 1% of the dry diet. The combined technique of cooking-extrusion of a basal diet followed by coating of a lipid emulsion proved to be a valid technique to prepare diets for studying quantitative fatty acid requirements of weaning and first ongrowing stages of marine fish. A standard diet with open formulation is proposed.