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Barley Studied as a High-protein Fish Food

15 July 2014

US - A process that improves the nutritional value of barley for use in fish feed has been developed by scientists at the US Department of Agriculture (USDA) and Montana Microbial Products LLC (MMP) of Missoula, Montana.

Barley typically contains about 10 to12 per cent protein, but 40 to 60 per cent protein is needed in diets of carnivorous fish like rainbow trout and salmon. The new enzymatic process patented by the Agricultural Research Service (ARS) and MMP concentrates protein by removing the carbohydrates in barley and turning them into an ethanol coproduct, utilizing all the nutrients in the grain.

ARS is USDA's principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.

The new high-protein product produced by this technology should help fill the gap for more plant-based protein sources as alternatives to fishmeal, which is made from small ocean fish, according to fish physiologist Rick Barrows, with the ARS Small Grains and Potato Germplasm Research Unit in Aberdeen, Idaho. In addition, barley protein concentrate has less variability in composition and is less expensive than most fishmeals.

Barrows, who works in Bozeman, Montana, and his team tested barley protein concentrate in rainbow trout and found digestibility—the percentage of nutrients available to the fish—to be as high as 95 per cent. The product also was tested in Atlantic salmon by research leader William Wolters and fish physiologist Gary Burr at the ARS National Cold Water Marine Aquaculture Center in Franklin, Maine.

Atlantic salmon were fed a diet containing either 11 per cent or 22 per cent barley protein concentrate. The growth of those salmon was not significantly different from salmon fed a standard fishmeal diet. Also, the fish that ate the 22 per cent barley protein concentrate diet had significantly greater energy retention compared to fish fed the other diets. Higher energy retention demonstrates that the fish are using the feed more efficiently.

MMP has built a commercial prototype plant in Montana to produce barley protein concentrate for trout feeding trials. The company also plans to build a commercial facility in the near future.

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