Growth Performance of Atlantic Salmon Smolts Fed Diets Containing Heterotrophic Algal Biomass as Replacement of Fish Oil

Abstract

AbstractOne of the most widely cultured finfish in the world is the Atlantic Salmon Salmo salar, with over 2 million metric tons produced per year. Atlantic Salmon fillets are widely accepted by consumers as a source of long‐chain omega‐3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). As feed producers shift from using marine ingredients to more terrestrial ingredients, producers need to monitor the fatty acid profiles of the fillets. Juvenile Atlantic Salmon (~280 g) were fed one of four diets during a 16‐week feeding trial. The four diets were formulated with increasing amounts (0, 5, 10, and 15%) of a DHA‐rich, whole dried algae (DHA = 20.3%) to reduce fish oil (12.7, 7.85, 3.00, and 0%, respectively). There were no significant differences in weight gain, feed efficiency, or the thermal growth coefficient. The proximate composition of the whole fish also did not vary due to dietary treatment. The amount of DHA in the fillets increased with increasing inclusion of the DHA‐rich algal biomass. The organoleptic properties (basic and aromatic tastes) also did not vary due to diet. The apparent digestibility coefficient was about 66%. Overall, including a heterotrophic algal biomass in the diets of Atlantic Salmon while reducing fish oil supported equivalent growth while maintaining levels of long‐chain omega‐3 fatty acids in the fillets.