Effects of temperature and feed composition on essential fatty acid (n-3 and n-6) retention in Atlantic salmon (Salmo salar L.) parr

• Published in: Fish physiology and biochemistry Vol. 29; no. 2; pp. 133 - 140
• Main Authors: Bendiksen, E.Å., Jobling, M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.01.2003
• Subjects: Abbreviations; Arachidonic acid; Body condition; Composition; Diet; Docosahexaenoic acid; Eicosapentaenoic acid; Fatty acids; Feed composition; Feeds; Fish; Freshwater fishes; Low temperature; Marine fishes; Mass balance; Nutrition; Oil; Phospholipids; Polyunsaturated fatty acids; Rapeseed; Retention; Salmo salar; Salmon; Temperature effects; Triglycerides
• ISSN: 0920-1742; 1573-5168
• DOI: 10.1023/B:FISH.0000035937.68098.83

Retentions of total n-3 and n-6 essential fatty acids (EFAs) were assessed in Atlantic salmon (Salmo salar L.) parr held at 8 °C and 2 °C until they increased in weight from ca. 19 g to 38 g. Feeds contained sandeel oil or a rapeseed:linseed oil blend at 21 and 34% dietary fat. EFA retention efficiencies [(g EFA gained g EFA ingested-1) × 100] were estimated by the 'mass balance method' from measurements of feed intake, changes in biomass for each tank of fish, and fatty acid compositions of the feeds and fish. The n-3 EFA retentions were higher (overall mean 71%) across feed treatments and temperatures than the n-6 EFA retentions (overall mean 63%). Retentions of the n-3 fatty acids were higher in the fish given the feeds with the lower fat content (77% vs. 65%), implying improved retention with reduced n-3 EFA availability. n-3 EFA retention tended to be higher at 2 °C than at 8 °C, although this was not consistent across feeds. At low temperature there was very high retention of the n-3 EFAs in feeds containing sandeel oil (80%). Such high retention may represent an adaptation response to low temperature. Lower n-6 EFA retentions imply that more n-6 fatty acids were metabolized than n-3 EFAs. Feed oil influenced retention of the n-6 fatty acids, retention being lower for the salmon parr given the feeds containing sandeel oil (56% vs. 71%). This could indicate a higher tissue deposition of n-6 fatty acids when they are freely available via the diet. Abbreviations: AA – arachidonic acid (C20:4 n-6); DHA – docosahexaenoic acid (C22:6 n-3); EFA – essential fatty acid; EPA – eicosapentaenoic acid (C20:5 n-3); HUFA – highly-unsaturated fatty acid (\ge4 double bonds); MUFA – monounsaturated fatty acid (1 double bond); PL – phospholipid; PUFA – poly-unsaturated fatty acids (\ge2 double bonds); SFA – saturated fatty acid (no double bond); TAG – triacylglycerol.