Salmon genes can give more omega-3

There is less omega-3 in the fillet when salmon are fed plant-based feed. However, the scientists know that salmon have a certain capacity to convert omega-3 fatty acids from plant oil to marine omega-3. They will now receive help from the salmon's genes to increase this capacity, reports www.megafishnet.com with reference to Nofima.

The goal is to make salmon a net producer of omega-3, or in other words that the content of marine omega-3 in the salmon muscle becomes higher than that supplied through the feed it eats.

Gerd Marit Berge is a feed scientist at Nofima, and is focussed on the fact that we balance considerations about the amount of omega-3 in the fillet with considerations about the limited resources in the sea.

"We would certainly like the salmon we eat to be rich in marine omega-3, but at the same time out of consideration to resources it is essential to reduce the use of fish oil, which is the main source of marine omega-3," says Berge. "It is wrong to claim large amounts of valuable fish oil just for salmon feed. We therefore need to find other ways to limit the disadvantage of reducing the content of an important omega-3 source in the feed."
Enzymes are the key

One way the scientists will try to limit the disadvantage is to put together different combinations of oils in feed, test them out on the fish and find out which combinations result in the best possible utilisation of omega-3.

"By using cell cultures, we can test many different combinations so that we can more quickly arrive at the best ones," says Berge. "We will then test these out on salmon families that we believe are good and less good at utilising the resources."

The scientists will search for a gene that produces the enzyme desaturase in the salmon families of breeding company SalmoBreed. They will select families with high and low expression of desaturase for the feeding trial.

This enzyme is an important brick in the conversion from short to long omega-3 fatty acids, or in other words it is central in the conversion of a fatty acid that plants are rich in to fatty acids that fish oil is rich in.
Unique breeding programme

Håvard Bakke from SalmoBreed thinks this is an exciting project because it is a totally new way of working for them.

"We have never before selected families based on enzyme analyses. It will be exciting to see how much significance genes have on the salmon's ability to form marine omega-3 from plant oils," says Bakke. "This ability can be valuable in the future when there is increasingly less marine omega-3 in the feed."

"By maximising this ability, we can preserve the fat quality of the fish as food for human consumption and have a sustainable utilisation of the feed resources," concludes Berge.

This project is supported by the Research Council of Norway. It is headed by Nofima and run in collaboration with the Norwegian University of Life Sciences (UMB), the Swedish University of Agricultural Sciences (SLU), SalmoBreed AS and BioMar AS.