Effect of soy oil containing stearidonic acid on growth performance and fillet fatty acid composition of Atlantic salmon

The effects of stearidonic acid (SDA; 18:4n-3) derived from SDA-enhanced, genetically modified soybeans (Monsanto Company, St Louis, MO, USA) on growth performance and fatty acid (FA) composition of large Atlantic salmon (Salmo salar; 2.1 kg initial weight) were evaluated. There was a stepwise decrease in feed intake and subsequent weight gain of immature Atlantic salmon with increased replacement of fish oil by SDA soy oil from 0%, 50% to 100% added oil. SDA increased and n-3 highly unsaturated FA (n-3 HUFA; eicosapentaenoic acid + docosahexaenoic acid) decreased in the diet and corresponding fillet with increased SDA oil inclusion. Salmon with the same weight gain fed SDA oil compared with rapeseed oil at 50% fish oil replacement had similar n-3 HUFA fillet levels indicating little or no increased synthesis of n-3 HUFA from SDA for deposition in the fillet. However, elongation of dietary SDA to 20:4n-3 for deposition in the fillet of SDA oil fed fish was indicated. The increased SDA and 20:4n-3 in the fillet of Atlantic salmon fed SDA oil compared with rapeseed oil at 50% fish oil replacement may be more effective as precursors for EPA in humans than 18:3n-3 which was in the fillet at similar levels.