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Doubling Production from Available Fish Oil

SWEDEN - New research has opened the possibility that fish feed makers could double production from the currently available fish oil while providing farmed fish that still have the omega-3 fatty acid content that make fish a healthy food for the consumer.

Research at the Swedish University of Agricultural Sciences has revealed that a component of sesame oil added to fish feed may enable salmonid fish to produce the long-chain omega-3 fatty acid DHA from linolenic acid in plant oils. The research won the DSM Innovation Award at AquaVision 2008

According to Fish Farmer, Professor Jana Pickova, who led the research team, explained. "We knew from the literature that substances from many plant species are known to be active modulators in animal metabolism. Examples for this are antioxidants, plant estrogens and others. For example, there were reports from Japan that showed increases in omega-6 levels, so we thought it could be possible to stimulate omega-3 levels in the same way. We explored the potential of some of these compounds to modulate lipid metabolism to provide a positive effect on the content of EPA and DHA in the fish fillets.

"My colleague Sofia Trattner had investigated sesame and the composition of sesame oil. This led us to test a component of the oil, a lignan known as sesamin, in feed for rainbow trout. The experimental feeds used only linseed and sunflower oils and were made with de-fatted fishmeal to minimise the marine oil present. Only one had sesamin.

"The fish fed on the sesamin diet had significantly higher levels of DHA, up by around 37%, compared with the control group on the non-sesamin diet. This extra DHA came from a metabolic process in the fish, stimulated by the sesamin, that converted linolenic acid into DHA. We did not see any adverse effects on fish growth or health. In a parallel study, we found similar results in which a-lipoic acid increased EPA levels."

The research was recognised at the AquaVision 2008 conference in Stavanger, Norway, by the presentation of the first DSM Innovation Award of 10,000 to the Swedish research pair, reports Fish Farmer.

Ellen Hardy

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