Product Descriptions

Many feed products can result from the ethanol production process. They are described here. Choose a category to go directly to information about:

• Managing Distillers Grains and Cattle Feeding 2007 Workshop presentations

• Co-Products of the Dry Milling Industry (distillers grains and solubles)


• Nutrient Profiles


• Distillers Grains Calculator


• Iowa Distillers Grains Suppliers – Local Sales


• Distillers Grains Suppliers


• The Average Nutritional Profile of DDGS


• Co-Products of the Wet Milling Industry (extractives, germ meal, gluten feed, gluten meal)


• New Generation Co-Products


• Distillers Grains and Manure Management

Co-Products of the Dry Milling Industry

Corn is about two-thirds starch, which is converted to ethanol and carbon dioxide during a distilling and fermentation process. The remaining nutrients in corn, such as protein, fat, minerals and vitamins, are concentrated in three different ways and end up as distillers grains or condensed distillers solubles. Distillers grains are a co-product of the dry mill process used to make ethanol from corn.

Corn distillers grains contain the remaining nutrients after the corn starch is fermented to alcohol. The distillers grains can be sold wet or dried. Wet distillers grains are higher in protein and energy than corn gluten feed because gluten and oil remain in distillers grains. When distillers grains are dried they lose some energy value compared to wet products. Dried distillers grains and dried distillers grains with solubles are marketed widely around the world as a feed commodity.

Corn distillers dried grains (DDG) is obtained after the removal of ethyl alcohol by distillation from the yeast fermentation of a grain or a grain mixture by separating the resultant coarse grain faction of the whole stillage and drying it by methods employed in the grain distilling industry.

Corn distillers dried grains/solubles (DDGS) are recovered in the distillery and contain all the nutrients from the incoming corn minus the starch. Thus, the DDGS has at least threefold the nutrients as the incoming grain. Since the stillage is recycled, the ratio of these more valuable amino acid types continues to increase so that eventually they represent approximately 16% of the final DDGS's amino acid content. No other feed ingredient results from such a great percentage of microbial products and their back stocking. DDGS typically analyzes at 27% protein, 11% fat and 9% fiber.

Corn condensed distillers solubles (CDS) is a term generally used to refer to the evaporated co-products of the grain fermentation industry. Most of the CDS is added to the dried grains, but some is available as a liquid feed ingredient. On a dry matter basis CDS typically is 29% protein, 9% fat and 4% fiber. The solubles are an excellent source of vitamins and minerals, including phosphorus and potassium. CDS can be dried to 5% moisture and marketed, but generally the dry matter content is between 25-50%.

Wet distillers grains (WDG) can be sold as livestock feed or dried into distillers grains (DDG). If syrup is added to wet distillers grains and dried, the resulting product is referred to as distillers dried gains with solubles (DDGS).

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Iowa Distillers Grains Suppliers – Local Sales

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Average Nutritional Profile of DDGS

As starch is removed for conversion to ethanol, fat, minerals, vitamins and fiber are present in the spent grains at a higher proportion. Ethanol production results in a higher concentration of nutrients present from the corn, as well as synthesis of other nutrients. The yeast used to ferment the starch contributes positively when added back to the grains in the form of solubles. This concentration of protein, fiber, fat and minerals enhances the nutrient viability and value of DDGS as a specialty ingredient in the ration because of lower inclusion rates in the diet. By feeding a lower inclusion rate feedstuff, more space is left in the ration to meet the animal's nutritional requirements without exceeding recommended daily total dry matter intake.

Today, there is not a standard test done for distillers grains. AOAC standards are being considered for adoption by the ethanol industry to provide consistency. The University of Minnesota recently gathered samples from Midwest plants to perform the AOAC test and compare nutritional profiles. To read about the Midwest plant nutritional profiles, visit the University of Minnesota's website

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Co-Products of the Wet Milling Industry

Wet-milling produces four major co-products for the feed industry from the isolated steep water, bran, germ meal and gluten. Together these co-products represent about 25%-30% of the corn processed.

Condensed corn fermented extractives or corn steep liquor is a high-energy liquid feed ingredient. The protein value analyzes at 25% on a 50% solids basis. This product is sometimes combined with the corn gluten feed or may be sold as a pellet binder and is a source of B-vitamins and minerals.

Corn germ meal is golden-yellow and is mainly gluten, the high-protein portion of the corn kernel. Corn gluten meal typically analyzes at 20% protein, 2% fat and 9.5% fiber. It has an amino acid balance that makes it valuable in poultry and swine rations. It is also used as a carrier of liquid feed nutrients.

Corn gluten feed is an intermediate protein product that is rich in highly digestible fiber. It may or may not contain the condensed corn extractives. This product is sold as wet or dry. The bran and condensed extractives (sometimes germ meal) are combined and dried in a rotary dryer. The dried corn gluten feed is made into pellets to facilitate handling. It analyzes typically as 21% protein, 2.5% fat and 8% fiber. Wet corn gluten feed (45% dry matter) is similarly combined but not dried. It is a perishable product in 6-10 days and must be fed or stored in an anaerobic environment. These feeds are widely used in complete feeds for dairy and beef cattle, poultry, swine and pets.

Corn gluten meal is a high-protein concentrate typically supplied at 60% protein, 2.5% fat and 1% fiber. It is a valuable source of methionine. Corn gluten meal also has a level of xanthophylls, which offers the poultry feed formulators an efficient yellow pigmenting ingredient. Corn gluten meal also is excellent cattle feed providing a high level of rumen bypass protein.

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New Generation Co-Products

Renewable fuels refineries are constantly seeking improvements in operating efficiency, product diversification and innovative measures to take them to the next level of value-added processing.  This new generation of technology is improving the bottom line, reducing energy inputs, and opening doors for new co-products.

Corn Oil Extraction
Removing crude corn oil from the syrup before it is mixed with distillers dried grains provides a potential feedstock for biodiesel production.  This technology creates a new co-product and additional revenue stream for ethanol refineries along with reduced emissions and energy use. The resulting feed co-products have a higher protein content and improved flowability for better product handling and storage.

Corn Fractionation
Increasing ethanol production from a single bushel of corn is now being done by separating the corn kernel into its various components instead of grinding the entire kernel.  Additional starch from the endosperm is available through this method for fermenting into ethanol.  The germ and fiber are used as feed co-products, providing extra protein and improved flowability. These advancements also reduce refinery energy inputs and emissions.

Renewable Processing Power
High natural gas prices are forcing renewable fuels refineries to look for creative energy sources to provide heat, steam and electricity.  One novel approach is to burn the syrup from the refinery process in a fluidized bed reactor to generate heat and steam.  Using syrup as an energy source reduces natural gas usage by 60% and cuts down on dryer use by up to 50%.  Consideration is being given to pelletizing the ash from the fluidized bed reactor for use as a commercial fertilizer.

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