Creating value
2013
nofima.no
36
financed by:
The Norwegian Seafood
Research Fund
Partner:
The National Institute of
Nutrition and Seafood
Research
Scientists are seeking answers about the amount of the omega-3 fatty acids EPA and DHA that salmon and trout need to maintain good health.
photo: Jon-Are Berg-Jacobsen © nofima
Aquaculture is one of the fastest growing food producing
sectors. A major limitation to further growth is the scar-
city of fish oils for use in fish feed. Scientists are seeking
answers about the safe lower dietary levels of fish oils
that secure the salmon and trout good health.
They have collated the current knowledge and
identified what knowledge is needed in order to know
the fish’s minimum needs for EPA and DHA. More than
200 scientific publications have been reviewed. It is
documented that the fatty acid composition of feed
is important for fish welfare, but we do not know the
optimal dietary fatty acid composition required to secure
good disease resistance.
“We need knowledge about which fatty acid com-
positions that makes the fish less susceptible to stress
and viral and bacterial infections. We also need more
knowledge about the long-term effects of low EPA and
DHA levels in feed on fish health,” says Nofima Senior
Scientist Bente Ruyter.
Different requirements in different life stages:
Salmon and trout have several vulnerable life stages,
such as the early larval stage, smoltification and sexual
maturation. More knowledge is needed about the nutri-
tional requirements in these phases.
In the freshwater phase, the fish need a minimum
of 1% EPA and DHA in the feed. In the seawater phase,
studies indicate that salmon tolerate high levels of
various plant oils in the feed without negative effects
on growth. However, the knowledge about long-term
effects on fish health is inadequate, as the majority of
trials are limited to short phases of fish life.
“Knowledge about epigenetic regulations (or changes
in DNA that are expressed in later life stages and trans-
ferred to the next generation) can be an important part
of the future work to optimize the potential of salmon
and trout as good net producers of EPA and DHA,” says
Ruyter.
Scientists are seeking good substitutes for the marine ingredients in
salmon feed due to restricted resources from the sea.
Seeking optimal salmon diet
