Sesame extract could double fish feed production from available fish oil

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. Potentially this discovery, which won the DSM Innovation Award at AquaVision 2008, could enable fish feed makers to 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.

Jana Pickova

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 -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. The initial trials were with rainbow trout weighing 50g at the outset and their work is continuing with a second trial beginning with fish at 300g. The results will become available next spring.

Professor Pickova concluded, “If this work can be translated into commercial practice, we can significantly increase the amount of fish feed we produce from the fish oil that is sustainably available.”

Fishmeal also

At the same conference, Knut Nesse of Skretting Salmon Feeds announced that 800,000 salmon produced at the Centre for Aquaculture Competence (CAC) in Norway had yielded more fish protein than was used to produce their feed, without reducing the omega-3 level in the fish flesh. (See story).

The results demonstrate commercially farmed salmon can be net fish protein producers, producing more fish protein than comes from the wild fish used in the feed.

These two advances announced at AquaVision 2008 clearly demonstrate that limits in the supply of marine raw materials do not need to frustrate future growth in the aquaculture industry.