ONTOGENY OF LIPID DIGESTION AND EFFECTS OF FEEDING PRE-DIGESTED LIPIDS TO ATLANTIC COD (GADUS MORHUA) LARVAE

Lipids provide cod larvae with energy and essential fatty acids, the latter being structural components of biological membranes and precursors for the eicosanoids; signalling molecules which participate in regulation of a range of biological processes. Un til now, research on dietary lipids for marine fish larvae has mainly focussed on optimising the fatty acid composition. In this application, we propose to increase the capacity for lipid digestion and absorption in developing cod larvae by feeding pre-di gested lipid. We will compare the absorption of triacylglycerol (TAG) and phospholipids (PL, intact lipid) with monoacylglycerol and lysoPL (pre-digested lipid). Absorption will be measured using the tube feeding technique developed by Rønnestad et al., ( 2001). We will also measure gene expression and activity of the lipolytic enzymes, bile activated lipase (BAL) and pancreatic phospholipase A2 (PLA2) during ontogeny. A feeding trial we be performed, using formulated diets, where we feed different combina tions of TAG, PL, MAG and lysoPL to cod larvae and where larval performance with respect to growth, survival and deformities will be measured, together with lipid uptake and digestive hormone status of the larvae. The project will develop new knowledge on digestion, absorption and metabolism of lipids in marine fish larvae. This may lead to better utilisation of lipids during production of cod larvae and give better growth and survival of cod in commercial hatcheries.