Distillers Dried Grains with Solubles (DDGS) is the most common coproduct from many ethanol plants. It is typically dried to about 10% moisture content, to ensure a long shelf life and to reduce flowability issues during storage and transport. It can be transported by truck, rail, and boat to local livestock producers, throughout the country, or even to overseas markets. DDGS has increasingly been exported to globally in recent years.
Most ethanol plants in are dry-grind facilities which use starch from corn to produce ethanol and the remainder of the corn kernel is used to produce a variety of wet and dried distillers grains co-products including DDGS. In dry-grind ethanol production, each bushel of corn (25.4 kg) produces about 11.8 liters of ethanol, 7.7 kg of DDGS, and carbon dioxide. Wet mills represent a significant, but smaller proportion of the U.S. ethanol industry and produce corn gluten feed, corn gluten meal, and corn germ meal as the primary co-products.
Animal feed is the most important use for ethanol coproducts (more than 99%, in fact). Coproducts contain nutrient profiles that parallel the grain that was used for fermentation (most of the starch is used by the microbes, so the remaining nutrients are concentrated by approximately 3x), and they are highly digestible. It has been shown that DDGS can replace corn in livestock diets on a 1:1 up to a 1.2:1 level, depending on the species.
The majority of distillers grains are used in beef and dairy feeds, because ruminants can easily utilize high levels of fibre. But, monogastrics (including swine, poultry, fish, and others) have been shown to readily digest DDGS as well, and these markets continue to gain importance. Many feeding trials have been conducted on coproducts over the years, for both monogastrics and ruminants, in order to increase and optimize coproduct use.