A component of sesame oil added to fish feed may enable salmon and trout to produce the long-chain omega-3 fatty acid DHA (docosahexaenoic acid) from linolenic acid in plant oils, according to researchers at the Swedish University of Agricultural Sciences.
The discovery, which won the DSM Innovation Award at AquaVision 2008 in Stavanger, Norway, this week, may allow manufacturers to double fish-feed production without using more fish oil.
"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," says head researcher Jana Pickova.
Pickova and his colleague, Sofia Trattner, were awarded 10,000 euros ($14,024) for their work.
Skretting Salmon Feeds raised 800,000 salmon at Norway's Centre for Aquaculture Competence that yielded more fish protein than was used to produce the fish feed without reducing the omega-3 level in the fish flesh, says Knut Nesse of Skretting, one of the world's largest fish-feed manufacturers.
"Sofia Trattner had investigated sesame and the composition of sesame oil," says Pickova. "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 percent, compared with the control group on the non-sesamin diet," he explains. "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."
