Strategies, Benefits, and Challenges of Feeding Ethanol Byproducts to Dairy and Beef Cattle

Ethanol byproducts or coproducts (I may use the two terms interchangeably) result from the fermentation of grains, typically corn, to produce ethanol – either for fuel use or for human consumption plus distillers grains and possibly other byproducts. Most of the ethanol produced in the U.S.A. today is via dry grinding, with dried distillers grains plus solubles (DDGS) as the main byproduct (Rausch and Belyea, 2006). Quantitatively, dry grind processing of 100 kg of corn produces approximately 40.2 L of ethanol, 32.3 kg of DDGS, and 32.3 kg of carbon dioxide. Wet milling is usually used for producing corn oil, corn sweeteners such as dextrose and high fructose corn syrup, but the starch can be fermented to produce ethanol. Byproducts of this process include corn gluten feed (CGF) and corn gluten meal (CGM). The CGF consists mainly of corn bran and steep liquor. Corn gluten meal is a high protein coproduct that also arises from wet milling while corn germ meal remains after extraction of oil from the corn germ. Quantitatively, one obtains approximately 67.2% corn starch (which can be fermented to ethanol), 19.6% CGF, 5.7% CGM, and 7.5% corn germ (50% oil) from the wet milling of corn (Long, 1985). Distillers grains and CGF can both be fed wet or dried with similar results.