INFLUENCE OF DIETARY FATTY-ACIDS ON THE GLYCEROPHOSPHOLIPID COMPOSITION IN ORGANS OF COD (GADUS-MORHUA)

Cod (mean start weight of 26 g) were fed three diets for 15 months, each based on a dry pellet coated at a level of 9 g/100 g with soybean oil, capelin oil or sardine oil. The fatty acid compositions of neutral lipids and four glycerophospholipids of white muscle, liver, gills and heart were determined. The fatty acid composition of dietary lipids influenced the composition of neutral lipids in all organs. Linoleic acid (18:2n-6) from soybean oil was selectively incorporated into phosphatidylcholine of the four tissues. Similar levels of 20:5n-3 and 22:6n-3 in phosphatidylcholine and phosphatidylethanolamine were found in all organs from cod fed capelin oil and sardine oil in spite of highly differentiated feed fatty acid levels. The polyunsaturated fatty acid (PUFA) composition of phosphatidylinositol was least influenced by dietary lipids. The preferred monoenoic fatty acid in phospholipids of cod was 18:1n-9, independent of dietary intake, whereas the longer chain monoenoic acids seemed to be preferentially catabolized. The results suggest that 20:4n-6 as well as 20:5n-3 and 22:6n-3 fatty acids are essential for cod.