Ethanol Co-Products Could Lower Cost of Freshwater
Fish Production By
Laura McGinnis October 19, 2007
Add this to the list of ethanol's potential benefits: lowering the
cost of fish production.
Fish feed is a major expense for many aquaculture operations. New
research by Agricultural Research Service (ARS) scientists shows that ethanol
co-products can provide protein for fish feeds at a lower cost than the
soybean-corn combinations commonly used.
The recent proliferation of ethanol processing facilities has led to a
surplus of distiller's dried grains with solubles, or DDGSa nutrient-rich
processing co-product that is often used to feed livestock.
DDGS is relatively protein-rich and lacks some of the undesirable
characteristics that make many plant protein sources less suitable for use in
fish feeds. In addition, DDGS is cheaper and more palatable to fish than
soybean-corn combinations. However, it lacks some essential amino acids, such
In the ARS
Animal Health Research Unit at Auburn, Ala., nutrition scientist
Lim and his colleagues are evaluating how diets including DDGS influence
growth performance and disease resistance in catfish and tilapia.
The scientists gave the fish feeds that included 0, 10, 20, 30 or 40
percent DDGS. All five feeds had similar levels of energy, protein and fat.
Results showed that tilapia thrive on feed with up to 20 percent DDGS. Adding
supplemental lysine to the feed increased that percentage to 40 percent.
The scientists found that catfish thrived on feed comprising up to 40
percent DDGS plus lysine. In addition, they observed that catfish raised on
diets that included DDGS demonstrated greater resistance to at least one major
disease: enteric septicemia of catfish. Catfish raised on DDGS-containing diets
were more likely to resist infection.
Surviving catfish raised on a diet without DDGS had fewer antibodies
than those raised on the DDGS feedparticularly fish on the 20 percent
DDGS diet, whose antibodies were significantly higher than those of the control
This work has potential economic benefits for both ethanol and
aquaculture. Finding markets for DDGS is essential to economical ethanol
production. And substituting soybean-corn combinations with a cheaper protein
source could help reduce the cost of fish feed, thereby reducing overall
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.