The effect of dietary lipid on polyunsaturated fatty acid metabolism in Atlantic salmon ( Salmo salar) undergoing parr‐smolt transformation

• Published in: Lipids
• Main Authors: Bell, J. Gordon, Tocher, Douglas R., Farndale, Bruce M., Cox, David I., McKinney, Richard W., Sargent, John R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1007/s11745-997-0066-4; https://onlinelibrary.wiley.com/doi/full/10.1007/s11745-997-0066-4

Abstract The aim of this study was to measure the changes in lipid metabolism which occur during smoltification and seawater transfer in Atlantic salmon ( Salmo salar ). Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO) or a blend of linseed and rapeseed oils, vegetable oil (VO), from October (week 0) to seawater transfer in May (week 26). From May to August (weeks 26–43), all fish were fed a fish oil‐containing diet. Fatty acyl desaturation and elongation activity were followed in isolated hepatocytes incubated with radioactive 18:3n−3 and 18:2n−6. Metabolism of 18:3n−3 was consistently around 5‐fold greater than metabolism of 18:2n−6, and total metabolism of both substrate polyunsaturated fatty acids (PUFA) was increased in fish fed both VO and FO up to seawater transfer after which desaturation activities were reduced. Desaturation activities with both 18:3n−3 and 18:2n−6 were significantly greater in fish fed VO, compared to fish fed FO, at 22 and 26 wk. Arachidonic acid (20:4n−6; AA) in liver polar lipids (PL) of fish fed VO increased consistently from weeks 0–22 but varied after seawater transfer. In fish fed FO, AA in liver PL remained constant up to week 17 before increasing at seawater transfer and leveling off thereafter. Eicosapentaenoic acid (20:5n−3; EPA) in liver PL of fish fed VO decreased significantly from week 0–22 before rising at seawater transfer and increasing rapidly posttransfer. EPA in liver PL of fish fed FO showed a similar trend except EPA was always greater in the freshwater phase compared to fish fed VO. Docosahexaenoic acid (DHA) levels in liver PL of fish fed VO remained constant in the freshwater phase before increasing following seawater transfer. In fish fed FO, DHA in liver PL increased from weeks 0–17 reducing and leveling off postseawater transfer. The levels of PGF 2α and PGF 3α were measured in isolated gill cells stimulated with calcium ionophore A23187. PGF 2α production in fish fed VO increased significantly between 0–7 wk before ...