Technology developed in the US may open new market opportunities for barley growers
Fish physiologist Rick Barrows (right) captures trout from 182cm-diameter tanks for technician Jason Frost to weigh and measure. These trout were fed fishmeal-free, plant-based feed.
PHOTO: Stephen R Ausmus, USDA-ARS
Barley is not commonly used as an ingredient for fish food because of its low protein content, but researchers in the US have developed technology that fortifies its nutritional value.
In an article published in the US Department of Agriculture journal Agricultural Research, Agricultural Research Service (ARS) fish physiologist Dr Rick Barrows says feed barley contains 10 to 12 per cent protein, but aquaculture feed needs to contain 40 to 60 per cent protein.
To lift the protein content of barley, researchers developed an enzymatic process to remove the carbohydrates in barley, which are then turned into an ethanol co-product, using all of the grains nutrients.
Dr Barrows says the barley protein is not exposed to high temperatures during concentration, which keeps it digestible for fish.
In addition, barley protein concentrate has less variability in composition and is less expensive than most fishmeals.
In tests on Rainbow Trout, protein digestibility and amino acid availability were measured in the mid-90 per cent range.
Research leader William Wolters and fish physiologist Gary Burr subsequently tested the barley protein on three groups of Atlantic Salmon.
The four-month trial compared the effects of adding either 11 per cent or 22 per cent barley protein concentrate to fish diets, with the third group of salmon fed a diet containing mostly fishmeal.
After four months, the researchers found no significant difference in growth among the three groups of salmon. However, salmon fed the diet containing 22 per cent barley protein concentrate had a higher feed conversion efficiency.
The researchers conclude that barley protein concentrate is an acceptable feed ingredient for Atlantic Salmon that should allow for performance similar to fishmeal at inclusion rates of up to 22 per cent.
ARS and Montana Microbial Products (MMP) have patented the barley processing technology, and MMP has built a prototype commercial plant in Montana to produce the alternative fish-feed ingredient. The company hopes to build a commercial facility if the prototype is a success.
Tasmanian agricultural contractor Greg McDonald says barley growers in that state are aware of the technology and are keen to see it available for use in creating a value-added product given the continuing expansion of the local aquaculture industry.
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