Sesame oil can increase salmon omega-3
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, 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."
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. 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.
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