October 22, 2007

DDGS can lower freshwater fish production

Aside from livestock, ethanol byproducts have added aquaculture as one of its potential beneficiaries as it can lower cost of fish production, according to a new research by Agricultural Research Service (ARS).

ARS -- the chief scientific research agency of the US Department of Agriculture (USDA)-- showed that ethanol co-products, particularly DDGS (distillers' dried grain solubles), can provide protein for fish feeds at a lower cost than the soy-corn combinations commonly used. Fish feed is a major expense for many aquaculture operations.

DDGS is a nutrient-rich processing co-product that is often used to feed livestock. It is also rich in protein and lacks undesirable characteristics that make many plant protein sources less suitable for use in fish feeds. Moreover, it is also cheaper and more edible to fish than soy-corn combinations. However, it is deficient in essential amino acids such as lysine, says ARS.

In the ARS Aquatic Animal Health Research Unit at Auburn, Alabama nutrition scientist Chhorn Lim and his co-researchers are studying how diets including DDGS can improve growth 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 raised that percentage to 40 percent.

The scientists found that catfish fed with a diet of up to 40 percent DDGS plus lysine has improved. In addition, it also exhibited greater resistance to at least one major disease: enteric septicemia of catfish, hence, the conclusion that 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 feed--particularly fish on the 20 percent

The results of the study showed potential economic benefits for both ethanol and aquaculture, said ARS. Finding markets for DDGS is essential to economical ethanol production while substituting soy-corn combinations with a cheaper protein source could help reduce the cost of fish feed, thereby reducing overall production costs.