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

Abstract

One 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.

Effects of Replacing Fishmeal with Algal Biomass (Pavlova sp. 459) on Membrane Lipid Composition of Atlantic Salmon (Salmo salar) Parr Muscle and Liver Tissues

“…This demonstrates that Pav459 could be included in the feeds of Atlantic salmon at up to 20% of the diet without compromising growth and feed utilization parameters. The results of the present study are similar to other feeding trial studies in which the authors did not detect any significant effects on growth parameters when FM was partially replaced by different strains of AB in Atlantic salmon diets [30,31], hybrid striped bass diets [32], European seabass [33], and shrimp diets [34], just to mention a few. Although immunology, lipid oxidation, goblet cells, mucus production, and the microbiome were not a focus of this study, other studies that included microalgal biomass in feeds in aquaculture revealed positive results in enhancing immune response [35,36], decreasing nitric oxide [37], increasing goblet cell density in the anterior intestine [38], modulating mucosal immune function, and increasing microbiome diversity indices for microbial communities in the gut of fish fed diets with PUFA-rich microalgae compared with controls [36].…”