Overview

Distillers Dried Grains with Solubles

Distiller's Dried Grains with Solubles (DDGS) is a co-product of the distillery industries. Most (~98%) of the DDGS in North America comes from plants that produce ethanol for oxygenated fuels. The remaining 1 to 2% of DDGS is produced by the alcohol beverage industry.

Approximately 3.2 to 3.5 million metric tonnes of DDGS are produced annually in North America. Ethanol plants in Minnesota and South Dakota produce approximately 25% of this amount (850,000 to 900,000 tonnes) annually. Most of the ethanol plants in Minnesota and South Dakota are small, farmer owned, and relatively new (less than 10 years old). These plants are utilizing new technology (e.g. batch fermentation) and improved quality control procedures to produce a higher quality DDGS compared to some older, larger, privately owned ethanol plants. In recent years, some regions of the U.S. have required the use of oxygenated fuels (e.g. ethanol-gasoline blends) to reduce air pollution from automobile emissions. Because of the increased demand for ethanol, the production of DDGS is expected to double within the next few years, further increasing the quantity of DDGS available for use in livestock feeds.

Of the 3.2 million metric tonnes of DDGS produced annually in North America, about 700,000 metric tonnes are exported to countries in the European Union for use in livestock feeds. A very small amount of DDGS is exported to Mexico, leaving about 2.65 million metric tonnes available for domestic use in the U.S. and Canada.

In North America, over 80% of DDGS are used in ruminant diets. Currently, Minnesota is the only state in the U.S. where a significant amount of DDGS (40,000 to 50,000 tonnes annually) is fed to turkeys. Historically, less than 1% of the total annual production is fed to swine, but based upon recent research studies conducted at the University of Minnesota showing excellent nutritional value of DDGS in swine diets, its use is increasing in the pork industry.

Production and Composition of Distiller's By-Products

Distiller's dried grains with solubles are the dried residue remaining after the starch fraction of corn is fermented with selected yeasts and enzymes to produce ethanol and carbon dioxide. After complete fermentation, the alcohol is removed by distillation and the remaining fermentation residues are dried.

Historically, three types of residual co-products were produced: distiller's dried grains, distiller's dried solubles, and distiller's dried grains with solubles. Once the fermented mash was distilled, the soluble portion of the remaining residue was condensed by evaporation to produce condensed distiller's solubles. The course material remaining in the fermentation residues was the Distiller's Grains fraction. Both of these fractions were subsequently dried to produce either distiller's dried solubles (DDS) or distiller's dried grains (DDG).

Today, ethanol plants blend and dry these two residues to produce distiller's dried grains with solubles, which is the only form available to the feed industry. The Distiller's Dried Solubles fraction has the highest concentration of nutrients compared to DDG and DDGS. It is a rich source of vitamins, and is the lowest in fiber and highest in fat, yielding a DE value that is approximately 91% of that found in corn. Since DDGS is a blend of DDS and DDG, one would expect the nutrient composition of DDGS to be intermediate between DDS and DDG. This is generally the case with the following exceptions: crude protein, arginine, histidine, lysine, methionine, cystine, tryptophan, magnesium, sodium, sulfur, selenium, vitamin B12, and folacin.

Some ethanol plants use milo, wheat, or barley in the fermentation process, depending on geographical location and time of the year. As a result, nutrient composition can vary among DDGS sources. Because of the near complete fermentation of starch, the remaining amino acids, fat, minerals and vitamins increase approximately three-fold in concentration compared to levels found in corn. Despite the significant increase in crude protein, the poor amino acid balance of DDGS must be addressed when formulating swine and poultry diets.