Omega 3
The University of Idaho’s Aquaculture Research Institute and U.S. Department of Agriculture collaborative aquaculture research program has made a genetic discovery that should help rainbow trout farmers cut costs and operate more sustainably while producing a healthier product.
The team identified the genetic markers and processes associated with rainbow trout capable of storing high levels of healthy omega 3 fatty acids in their fillets while being fed a plant-based diet. Omega 3s have anti-inflammatory effects, and separate U of I research has shown that consumption of omega 3-rich trout fillets can improve children’s cognitive and emotional well-being.
Idaho’s Magic Valley is the nation’s No. 1 production region for farm-raised rainbow trout. Trout farms have traditionally raised fish on diets heavy in omega 3 fatty acids from fish meal and fish oil, which is costly and depletes the oceans of marine life. Feeds based on crop ingredients such as soy protein and canola oil can be produced renewably and at a far lower cost, but most trout are inefficient at producing omega 3s from plant-based feed.
“It gives producers the option to use a different strain of trout that can reduce their input costs while producing a very high-quality fish that might offer even better nutritional resources,” said Jacob Bledsoe, a U of I assistant professor and Extension specialist of aquaculture research who was among the study’s authors.
The team’s conclusions about the markers are corroborated by the favorable results of more than five generations of genetic selections in their trout-breeding program, based at the university’s Hagerman Fish Culture Experiment Station. The researchers have developed rainbow trout capable of accumulating omega 3s from plant-based feed at even greater levels than from a marine-based diet. Their genetics are already being incorporated by the region’s commercial trout farms.
“We wanted to see generational gain in that trait, and we’re confident now that we’ve been able to improve that trait over several generations so we can be confident our findings are valid,” Bledsoe said.
The most important markers they studied are associated with a trout’s level of fatty acid binding proteins, which bind onto lipids and traffic them to a fish’s liver, where they can be efficiently metabolized.
“We identified specific markers within the lipid pathway that could be important, and fatty acid binding protein was the predominant one,” Bledsoe said. “We were able to show that a fish’s level of fatty acid binding protein correlates tightly with the ability to deposit omega 3s. Genetically speaking, there’s a lot in the genome that controls the expression of fatty acid binding protein.”
Bledsoe believes the team’s research will improve aquaculture’s overall understanding of lipid pathways in fish and will be applied to the selective breeding of other aquatic species.
