Study: GM plant oil can replace fish oil in farmed salmon feed

Published on
February 16, 2015

Oil from genetically modified (GM) camelina, a member of the mustard family of plants, known as false flax, can be used instead of fish oil for feeding Atlantic salmon.

Trials carried out by scientists at Stirling University in Scotland have demonstrated that growth performance, feed efficiency, fish health and nutritional quality for human consumers were unaffected when dietary fish oil was substituted with oil from the GM plants.

Said Monica Betancor, who carried out the research at Stirling’s Institute of Aquaculture: “Our findings are highly significant because fish oil is a finite and limited resource. It’s very expensive and the increasing demands for it by the fish farming industry will not be met in the future. So we really need to develop effective alternatives like this one.”

The research was part of a collaborative project with Rothamsted Research in England where a crop of camelina was spliced with genes to produce an oil rich in the long chain polyunsaturated fatty acids, collectively known as “omega-3s,” found in fish.

Scientists at Rothamsted Research used five microalgal and fungal genes to engineer the camelina plants to generate a sustainable source of eicosapentaenoic acid (EPA), one of the two long chain omega-3 fatty acids found in fish oils. It is the first example of a new generation of so-called “nutraceuticals” — plants whose genetic structure has been altered to introduce health-boosting properties.

While wild fish accumulate omega-3 fish oils through the consumption of other organisms in the marine food chain, farmed fish grown in cages are unable to absorb sufficient omega-3 fatty acids in this way so they have to be fed fish, usually in the form of fishmeal and fish oil. However, since there is a gap between the supply and demand for fish oils, new sources are required for the aquaculture industry and for direct human consumption.

Said Professor Douglas Tocher, project leader at Stirling university: ‘The development of these novel plant oils, tailored to human requirements, represents a sustainable way to farm fish with high levels of omega-3 fish oils that maintain their high nutritional value to the human consumer while preserving wild fish stocks.”

Professor Christine Williams, of the University of Reading, an expert on the impact of dietary fats in human health, said that long chain omega-3 fatty acids “are essential components of the developing brain and play a vital role in maintaining heart health. However they are made in the body in only very small amounts and need to be supplied in the diet.

‘This study showed this novel GM source of long chain omega-3 fatty acids was able to replace fish oils. This will allow farmed fish — the major source of fish in the U.K. diet — to retain the levels of essential long chain omega-3 fatty acids needed for human health.”

There is a vociferous anti-GM lobby as evidenced by the opposition in the USA to fast-growing GM salmon, although the use of GM ingredients in fish feed is accepted. However, in this case, anti-GM critics claim that omega-3 fish oils are implicated in the rise of prostate cancer and say that it is not clear whether GM-derived fish oils will be safe for human or animal consumption.

So what will happen next? There is obviously a long way to go before GM plant oils become a standard ingredient in salmon feeds, although it is equally obvious that an alternative source of omega-3 fatty acids for salmon feeds needs to be found.

The Marine Ingredients Organization (IFFO) said that in recent years the amount of fish oil added to each metric ton of farmed salmon feed has been reducing “due to an increased demand for salmon feed and a limited supply of fish oil.”

IFFO also made the point that since the amount of fish oil in farmed salmon feed is decreasing this has resulted in “some farmed salmon products containing less of the important omega-3 fatty acids, EPA and DHA, than before and consumers may need to eat more farmed salmon to maintain their recommended intake levels.”

So if consumers are to eat more farmed salmon, it is even more vital that an alternative for fish oil which provides omega-3 fatty acids can be developed for use in salmon feeds.

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