ARS | Publication request: Use of DDGS in diets of rainbow trout

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 31, 2011
Publication Date: February 7, 2012
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Welker, T.L., Barrows, F., Sealey, W. 2012. Use of DDGS in diets of rainbow trout. Aquaculture America Conference. 12:50.

Technical Abstract: Distiller’s dried grains with solubles (DDGS) are the principal byproducts of ethanol production from the fermentation of dry-milled whole grains. Most DDGS produced in North America is obtained from the fermentation of corn. However, the rapid growth and expansion of the ethanol bio-fuels industry has led to the use of other whole grains (wheat, barley, sorghum) and made DDGS readily available for use in animal feeds. Although the addition of DDGS in rainbow trout diets began in the 1940s, its current use in commercial feeds is limited. Part of the problem with addition of DDGS in trout feeds is that the product quality and nutritional value (crude protein and fat, carbohydrate content, essential amino acid composition, ash, etc.) varies depending on the processing facility and also the type of grain used. DDGS does not contain anti-nutritional factors typically found in most plant protein sources, but high levels of soluble fiber limit its use in trout feeds. However, even with quality issues, use of DDGS in rainbow trout diets does show promise as a partial protein replacement. Apparent digestibility of DDGS appears to be quite high in rainbow trout. Trout fed diets containing 30% corn DDGS showed an apparent digestibility of essential amino acids (EAA) of about 90%. Supplementation of phytase can further improve digestibility of several EAA. Research has also shown that DDGS can be added up to 15% of diet as a replacement of 50% of fish meal without requiring lysine and methionine supplementation, but the level of dietary DDGS can be increased to 22.5% as a substitute of 75% of fish meal with lysine and methionine addition. Feed ingredient and diet processing may be used to increase the nutritional value of DDGS to trout. Although diet processing method (cold pelleted vs. extrusion) does not improve the nutritional value of corn DDGS, reducing the fiber content through fractionation and sieving of wheat DDGS can increase the crude protein and digestible energy availability to rainbow trout. The current research on use of DDGS in rainbow trout diets has been conducted primarily with corn-derived DDGS. The protein, lipid, carbohydrate, and fiber contents and amino acid composition can vary depending on the grain used for DDGS production, and further research is needed to determine dietary inclusion levels of DDGS from these other grain sources. Furthermore, DDGS also contains other dietary factors, such as high levels of ß-glucan and B-complex vitamins, which may have positive or negative effects on trout health and fillet quality that will need to be evaluated.