US Fish & Wildlife Service


Date of this Version



Aquaculture 432 (2014) 7–14; doi: 10.1016/j.aquaculture.2014.03.026


US govt work


Grain distillers dried yeast (GDDY) is a single-cell protein obtained as a co-product during the production of fuel ethanol thatmay have potential as a protein replacement for rainbowtrout. The goal of this studywas to examine the suitability of GDDY as a replacement for fish meal on a digestible protein basis in rainbow trout diets. An in-vivo digestibility study was performed to determine the nutrient availability of GDDY. Subsequently, a control diet containing 42% digestible protein and 20% lipidwas formulated to replace fish meal proteinwith GDDY protein at eight different levels (0, 25, 37.5, 50, 62.5, 75, 87.5, and 100%). Diets were fed to juvenile rainbow trout stocked into four replicate tanks per dietary treatment (30 fish/tank) and fed twice daily for nine weeks. High GDDY inclusion rates significantly altered rainbow trout growth and feed conversion but not feed intake. There were no significant differences in production performance in fish fed the 25% GDDY and 37.5% GDDY diets when compared to fish fed the control diet, but further dietary fish meal replacement generally decreased fish performance. Further research iswarranted to determine why fish performance decreased with higher inclusion levels of GDDY in spite of similar feed intake among levels.