The ethanol industry is growing rapidly as demands for renewable fuels increase. This trend is especially noticeable in the northern and western areas of the Corn Belt (Iowa, Nebraska, Minnesota, and South Dakota). Consequently, availability of byproducts from ethanol production is increasing as well.

In general, most grain or oilseed processing is intended to extract either starch or oil from a grain or oilseed. In ethanol production, the goal is to turn corn starch into fuel grade alcohol (ethanol). Knowing what the processor wants to extract is the first step in understanding what the resulting byproduct should consist of from a nutrition standpoint. In most cases, processors are extracting starch or oil and the remaining materials (generally fiber, protein, and minerals) are usually more concentrated in the remaining byproduct than they are in the original grain or oilseed.

Distiller’s grains is a byproduct of the corn dry milling industry. As the name implies, corn is dry milled or hammer milled prior to the addition of water. The proper name for this byproduct in the AAFCO (Association of American Feed Control Officials) handbook is corn distiller’s dried grains plus solubles, but in most cases, it is simply referred to as dried distiller’s grains or distiller’s grains. Corn is by far the most common cereal grain feedstock used in ethanol production. It is important to note that plants that use wheat, barley, or other cereal grains will produce different byproducts.

In the ethanol production process, corn is ground, mixed with yeast and enzymes, and the resulting fermentation process produces ethanol from the corn starch. The mixture is distilled to remove the ethanol. The remaining mixture is centrifuged to separate the mash from the solubles. Some of the moisture in the remaining liquid byproduct is removed by heating to create condensed distiller’s solubles. This is added back to the mash to produce distiller’s grains plus solubles. This product can be marketed as a wet byproduct (wet distiller’s grain plus solubles; generally referred to as wet distiller’s grains) or it can be dried to produce dried distiller’s grains plus solubles. This byproduct contains unfermented corn proteins, corn oil, spent yeast cells, fermentation byproducts, and some soluble proteins that result from the fermentation process. Dried distiller’s grains can be difficult to pellet due to the fat content. Distiller’s grains also contain high levels of phosphorus and sulfur. High sulfur levels can cause polioencephalomalacia (commonly called ‘polio’) in cattle fed high levels of distiller’s grains and the high phosphorus level can pose manure management challenges.

Distiller’s grains can be used in a wide variety of beef cattle diets. For more detailed information see: NDSU: Feeding Coproducts of the Ethanol Industry to Beef Cattle