To raise strong, healthy rainbow trout for your backyard grill or for a white-tablecloth restaurant, fish farmers nourish this in-demand fish with a daily dose of at least a dozen essential vitamins.



Now, Agricultural Research Service (ARS) fish nutritionist Rick Barrows has made it easier for trout and other fish to get those vitamins. He's done that by developing an updated, preblended vitamin mix. It's a publicly available recipe, technically known as a "formula." It's already being added to fish feeds that are eagerly gobbled up not just by rainbow trout at fish farms and hatcheries, but also by rare and endangered species being raised in captivity for release into the wild.



A new, nonproprietary mix, according to Barrows, was needed to replace a decades-old formula that wasn't adapted to today's fish-feed processing technology. That technology, known as "extrusion processing," creates heat that can damage some vitamins. But the formula that Barrows developed takes this into account, compensating appropriately for estimated losses.



Barrows combed scientific journal articles and other published literature from around the globe to find the best available data on these losses, and then conducted additional collaborative research to fill in missing pieces of the puzzle. He used this information to determine the best quantity of each affected vitamin to use in the new premixed formula. It's just one of many steps that went into the two years of research and development that resulted in the science-based product dubbed "ARS-702."



In 2007, Barrows went public with the formula, which specifies the type and amount of each nutrient. Two major manufacturers of vitamins now make the mix which, in turn, has been added by feedmakers to more than 700,000 pounds of fish feeds.



Barrows, who is with the ARS Small Grains and Potato Germplasm Research Unit, Hagerman, Idaho, developed the vitamin mix in collaboration with ARS teammate and fish physiologist Gibson Gaylord at Hagerman, and Ron Hardy, director of the Aquaculture Research Institute at the University of Idaho.



SOURCE: USDA.