Over the last 20 years, the availability of fish oil has been on the decline. The aquaculture industry has responded by reducing the use of fish oil in feed formulas, replacing it with steadily increasing volumes of vegetable oil. However, conventional vegetable oils are not a one-to-one replacement for fish oil due to their lack of omega-3 fatty acids. Therefore, fish do not get the omega-3-rich diet they once did, and the quality and nutritional value of farmed fish has been impacted, as well as fish health and welfare.
Recently, researchers at the Norwegian Institute of Food, Fisheries and Aquaculture Research (NOFIMA) conducted a study, “A dose-response study with omega-3 rich canola oil as a novel source of docosahexaenoic acid (DHA) in feed for Atlantic salmon (Salmo salar) in seawater; effects on performance, tissue fatty acid composition, and fillet quality,”* examining the impact of a slight alteration to the currently used fish feed diet—replacing conventional canola oil with Aquaterra Advanced Omega-3 canola oil.
This study investigated the impact of increasing omega-3 nutrition with Aquaterra® omega-3 canola oil in farmed salmon diets on fish health and quality.
The study used Atlantic salmon raised in seawater cages and compared four diets where the amount of conventional canola oil was replaced with 0% (the control), 25%, 50%, and 100% Aquaterra Advanced Omega-3 canola oil. Aside from this adjustment, the ingredients of the feed were otherwise unaltered.
After 70 days, when the fish had reached a weight of 1.5 kilograms, they were harvested and samples were collected.
Researchers found that fish consuming more Aquaterra Advanced Omega-3 canola oil had a higher ratio of omega-3 to omega-6 and contained more ALA, EPA, and DHA than fish fed the conventional diet.
It was found that omega-3 intake had no impact on the weight or survival rate of the salmon, indicating that Aquaterra canola oil supported normal fish growth and health. Total protein present in the fish was also unaffected.
As the proportion of omega-3 canola oil present in the feed increased, the ratio of omega-3 to omega-6 present in the fish increased, as did the presence of ALA, EPA, and DHA fatty acids. Diets rich in these omega-3 fatty acids are understood to have anti-inflammatory properties and contribute to overall fish welfare. Improved skin and muscle color were observed as well, which consumers view as indicators of quality.
Increasing omega-3 in fish feeds has a direct impact on improving fish health and quality and also provides omega-3 rich salmon fillets to support human nutrition. While fish oil remains a limited resource, this study indicates Aquaterra is a simple and effective tool to increase omega-3 in fish feeds without increasing pressure on wild ocean resources.
Ruyter et al. (2022) A dose-response study with omega-3 rich canola oil as a novel source of docosahexaenoic acid (DHA) in feed for Atlantic salmon (Salmo salar) in seawater; effects on performance, tissue fatty acid composition, and fillet quality. Aquaculture. DOI: https://doi.org/10.1016/j.aquaculture.2022.738733