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Improving Fatty acid Composition in Rainbow Trout

16 September 2013

Scientists are seeking to improve the health benefits of rainbow trout by using dietary coriander oil along with vegetable oil to improve fatty acid composition in the fillet.

corriander troutThe health benefits of consuming omega-3 long chain polyunsaturated fatty acids such as EPA and DHA are well established.

The primary sources of these fatty acids in the human diet are through fish and seafood.

Researchers at the University of Saskatchewan, Department of Animal and Poultry Science, are studying new methods of improving the fatty acid composition of farmed fish.

As wild fish stocks decline, the aquaculture industry has become one of the fastest growing animal production sectors; this growth has increased demand for aquaculture feed production, which has caused further demand for fish oil.

Historically, fish are fed fish oil to increase levels of EPA and DHA. However, the fish oil supply is static; cost has increased and the industry is seeking low cost alternatives such as vegetable oils.

In a paper just published in the Canadian Journal of Animal Science, authors investigated strategies to increase long chain polyunsaturated fatty acids in rainbow trout.

They looked at the addition of coriander oil to vegetable oil-based diets to increase the bioconversion of alpha-linolenic acid to EPA and DHA.

The research team of K. M. Randall, M. J. T. Reaney and M. D. Drew from the University of Saskatchewan conducted a 16 week feeding trial to examine the effect of adding coriander oil to vegetable oil diets on the bioconversion of linoleic acid (LA; 18:2n-6) to arachidonic acid (ARA; 20:4n-6) and alpha-linolenic acid (ALA; 18:3n-3) to eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in rainbow trout.

The experimental treatments were a 4×2 factorial arrangement of diets using four dietary oils (fish, flax, canola and camelina oils) and two levels of coriander oil (0 and 5 g kg−1 inclusion levels).

Twenty-four tanks of triploid female rainbow trout (130 g initial weight; n=3) were used in the experiment.

The experiment lasted 112 days during which fish were fed to satiation twice per day.

The fatty acid composition of fillets from coriander-fed fish had increased concentrations of 20:5n-3 and 22:6n-3 (P<0.05).

Furthermore, a trend to increased (20:5n-3+22:6n-3)/20:4n-6 ratios was seen when coriander oil was added to the diet (P=0.067).

The results suggested that the addition of coriander oil to vegetable oil diets can significantly increase the bioconversion of 18:3n-3 to 20:5n-3 and 22:6n-3 in rainbow trout.

Their research showed that coriander-fed fish had increased concentrations of EPA and DHA in the whole fillet.

They also found that there were no negative effects on the health or growth of the fish.

“Our study shows that the addition of coriander oil to vegetable oil diets has the potential to improve the fillet fatty acid composition of farmed fish,” said Dr. Murray Drew, a Professor at the University of Saskatchewan’s College of Agriculture and Bioresources and co-author of the study.

“This discovery will contribute to the overall sustainability of aquaculture.”

In addition to finding alternative ways to increase the levels of EPA and DHA in farmed fish, innovative methods such as the use of coriander oil creates a new market for spice growers in Canada.

The article “Effect of dietary coriander oil and vegetable oil sources on fillet fatty acid composition of rainbow trout” was published online in the Canadian Journal of Animal Science.

September 2013

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