NORWAY February 23, 2012 – Experiments performed by the National Institute of Nutrition and Seafood Research (NIFES) have shown that salmon fed diets low in the marine omega-3 fatty acids contains more DHA (an important marine omega-3 fatty acid) than provided by the diet.
The diet of farmed salmon has traditionally been based primarily on food from the sea, in the form of fish-oil and fish-meal. However, marine resources will not be sufficient to satisfy the expected growth of the aquaculture industry, and feed producers will have to find alternative sources in the plant world. This means that the fish we eat will contain lower levels of the valuable marine fatty acids, but not as little as we might expect.
“When there are plenty of marine omega-3 fatty acids in their feed, salmon use them as a source of energy, but when the levels are low, they store them and may even produce more. And in this study, we found that salmon produced their own marine omega-3 fatty acids based on omega-3 from plants,” says NIFES research scientist Monica Sanden.
“We found that the fish body contained more DHA than what was provided by the diet, meaning that the fish had a net production of DHA”.
The experiment divided salmon into groups that were fed four different diets for a whole year. The diets contained different mixtures of plant and marine raw materials. In the most extreme diet, the scientists designed a diet in which 80 per cent of the fish-meal was replaced by plant protein, and 70 per cent of the fish-oil by vegetable oils. During three months, each fish produced 800 mg DHA. The European food safety authorities (EFSA) recommend a daily intake of 250 mg EPA and DHA for healthy persons.