|Rawles, Steven - Steve|
Submitted to: Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/18/2014
Publication Date: 4/3/2014
Citation: Hauptman, B., Barrows, F., Block, S., Gaylord, G., Patterson, J., Rawles, S.D., Sealey, W. 2014. Evaluation of grain distillers dried yeast as a fish meal substitute in practical-type diets of juvenile rainbow trout, Oncorhynchus mykiss. Aquaculture. 432:7-14. Interpretive Summary: Fishmeal is produced by harvesting small fish from the ocean like sardines and anchovies, and this meal has been the primary source of protein in fish diets for decades. Limited supply and increased demand has started a massive research effort to identify alternative protein sources to fishmeal. Ingredients that are a co-product of another industry are particularly interesting due to abundance and relative value. Ethanol yeast, also known as grain distillers dried yeast (GDDY) is a single-cell protein obtained as a co-product during the production of fuel ethanol. A study was conducted with the goal to determine the suitability of GDDY as a replacement for fishmeal in the diet of rainbow trout.
Technical Abstract: Grain distillers dried yeast (GDDY) is a single-cell protein obtained as a co-product during the production of fuel ethanol that may have potential as a protein replacement for rainbow trout. The goal of this study was to examine the suitability of GDDY as a replacement for fishmeal 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% lipid was formulated to replace fish meal protein with 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 is warranted to determine why fish performance decreased with higher inclusion levels of GDDY in spite of similar feed intake among levels.