The effect of total replacement of fish oil with DHA-Gold®and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant-based diet

This study investigated the effect of the replacement of fish oil (FO) with DHA-Gold (DHA-G)-supplemented plant oils (PO) in rainbow trout fed plant-protein-based diets. Five diets (450 mg g−1 digestible protein and 150 mg g−1 crude lipid) were fed to rainbow trout (initial weight 37 ± 0.5 g) for 12 weeks in a 15 °C recirculating water system. The lipid inclusion types and levels were FO, PO and PO with DHA-G supplemented at 30 mg g−1, 60 mg g−1 or 90 mg g−1 of the diet replacement for corn oil. Fish fed 90 mg g−1 DHA-G were significantly larger and consumed more feed than fish-fed PO or FO (218 g and 2.6% bwd−1 versus 181 g and 2.4% and 190 g and 2.3%, respectively). Feed conversion ratio was significantly increased in fish fed 90 mg g−1 DHA-G (0.99) as compared to fish-fed FO (0.90) and 30 mg g−1 DHA-G (0.91). Panellists found trout fillets from fish fed the 90 mg g−1 DHA-G diet to have significantly fishier aroma and flavour than fish fed the FO diet. Fatty acid analysis demonstrated that 60 mg g−1 or 90 mg g−1 DHA-G supplementation increased PO fed fish fillet DHA to fatty acid levels equivalent or higher than those fish fed a FO diet.