T2 News

Fish Go Nuts Over New Feed Ingredient

ARS fishmeal

Thanks to researchers at the Agricultural Research Service, a new feed ingredient made from tree nuts is available to fish farmers.

As the aquaculture (fish or shellfish farming) industry grows, so does the need for fish feed that's not dependent on the stagnant supply of fish meal made from captured marine fish protein and oils.

In an effort to develop ingredients high enough in protein for use as aquacultural feed, scientists at ARS’s Small Grains and Potato Germplasm Research Unit in Aberdeen, Idaho, worked with California-based company Adaptive Bio-Resources, LLC, to evaluate nuts as an alternative to fish meal.

ARS fish physiologist Rick Barrows modified the nutritional profile of nut materials to increase protein in a nut mixture made from pistachios and almonds that did not meet consumer standards for color, size and other qualities.

Adaptive Bio-Resources’ principal owner John Hamilton came up with the idea of using nuts that do not meet quality standards required by the California Nut Growers Association. Hamilton said the company has been making the nut meal ingredient for two years

Barrows and his colleagues evaluated the nut mixture in three separate studies. Their results proved that nut meal is highly digestible, palatable, and supports high growth rates in rainbow trout.

"If pistachios or almonds are too big, too small or too green, they're not used for human food, but they still have some value," said Barrows.

Fish fed the nut diet grew very quickly, according to Barrows. Young rainbow trout fed nut meal performed as well as those fed fish meal. Trout fed a diet containing 5 percent fish meal and 49 to 58 percent nut meal had survival and growth rates similar to those of trout fed a diet containing 55 percent fish meal. Trout fed nut meal in the study had weight gains equivalent to trout fed fish meal, except when the nut meal contained only almonds instead of almonds and pistachios.

Additional research on the nut meal is being conducted with collaborators at other institutions and at several commercial trout farms, Barrows said.

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Far West