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Stirling researchers use GM plants to replace fish oil in fish feeds

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A Camelina plant (photo by Rothamsted Research)

Oil from genetically modified (GM) Camelina plants – developed to produce essential omega-3 fatty acids in their seeds – has been found to be suitable for feeding Atlantic salmon, aiding the development of an alternative feed for the aquaculture industry to help preserve wild fish stocks and maintain nutritional value of farmed fish for humans.

In a collaborative research project between the University of Stirling and Rothamsted Research, scientists developed GM plants to produce high levels of essential omega-3 fish oils.

This significant development enables the plants to produce up to 20% of eicosapentaenoic acid (EPA), one of the two omega-3 nutrients conferring human health benefits, while preserving wild fish stocks.

Consumption of omega-3 fish oils, specifically long-chain polyunsaturated fatty acids (omega-3 LC-PUFA), has been linked with improved cardiovascular health and cognitive development. The primary dietary sources of these fatty acids for humans are marine fish - either wild or farmed. Fish accumulate the omega-3 fish oils through the consumption of other organisms in the marine food chain or, in farmed fish, through fishmeal and fish oil in feeds.

However, currently there is a gap between supply and demand for fish oils and new sources are required for the aquaculture industry and for direct human consumption.

The scientists used five microalgal and fungal genes to engineer the Camelina plants (Camelina sativa) to generate a sustainable source of omega-3 fish oils.

The oil extracted from these glasshouse-grown GM plants was then incorporated into fish feeds and Stirling scientists assessed the suitability of the feeds for Atlantic salmon.

The results of the study, published today in the journal Scientific Reports, demonstrated that growth performance, feed efficiency, fish health and nutritional quality for the human consumer were unaffected when dietary fish oil was substituted with oil from the GM plants.

The University of Stirling’s Dr Monica Betancor, a postdoctoral researcher who carried out the research at Stirling’s world-renowned Institute of Aquaculture, said: “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.”

Professor Johnathan Napier, leading the GM Camelina programme of research at Rothamsted Research, said: “It is very exciting for us to see the results of this study. For us the development of metabolically engineered Camelina plants has been a fascinating project.

“The findings of the present study are very encouraging as we have always worked towards providing a sustainable source for the omega-3 fish oils – our results here confirm another step in that direction.”

Professor Douglas Tocher, project lead at the University of Stirling, said: “There is a fundamental lack of the omega-3 essential fatty acids to satisfy the recommended dietary requirements for humans, and fish are our main dietary source.

“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.”