Distiller’s Dried Grains with Solubles (DDGS)
About
Distiller’s dried grains with solubles (DDGS) are the nutrient rich co-product of dry-milled ethanol production. DDGS utilization as a feed ingredient is well documented as both an energy and a protein supplement.
Combined, U.S. ethanol plants possess the capacity to produce more than 15 billion gallons of ethanol and 44 million metric tons of DDGS.
The U.S. beef cattle industry has been a major consumer of wet and dried corn distillers co-products for decades. In 2017, the U.S. beef industry was the greatest consumer of distillers co-products amongst all animal species, which represent 44 percent of total domestic use. As a result, there has been a significant amount of research conducted to evaluate the feeding value of corn distillers co-products to beef cattle, of which most has focused on optimizing use in niching feedlot beef cattle where it is used in the greatest quantities. Several excellent research summaries and feeding recommendations were been published 10 or more years ago (Erickson et al., 2005; Tjardes and Wright, 2002; Loy et al., 2005a; Loy et al., 2005b, Klopfenstein et al. (2008)). However, over 140 studies have been published since 2010 and the results of these studies are summarized in this chapter.
Corn DDGS is used as both a high-energy and mid-protein feed ingredient in beef cattle diets. In the U.S., nishing beef cattle have successfully been fed as much as 40 percent DDGS of ration dry matter as a replacement for corn grain. However, when adding more than 30 percent corn DDGS to the diet for use primarily as an energy source, it provides more protein and phosphorus than required for nishing feedlot cattle.
Energy
The primary carbohydrate fraction in DDGS is NDF (neutral detergent fiber). Much of the NDF in DDGS is obtained from the pericarp (bran) portion of the corn kernel which contains about 69 percent NDF, and is highly (87 percent) and rapidly (6.2 percent per hour) digested (DeHaan et al., 1983).
Because of the highly digestible and rapidly fermentable in DDGS, it is frequently used as a high energy and protein source in diets for feedlot finishing cattle. The corn oil present in DDGS is also a significant contributor to its energy content. Vander Pol et al. (2007) showed the digestibility of corn oil was 70 percent. However, as the level of fatty acid intake increases, fatty acid digestion decreases (Plascencia et al., 2003), which likely explains the decline in feeding value of DDGS when fed at high (greater than 30 percent) levels of the diet. Initial studies indicated that the NEgain of corn DDGS for beef cattle was 21 percent greater than the NE value of dry-rolled corn (Ham et al., 1994). A subsequent review by Tjardes and Wright (2002) indicated corn DDGS contains 2.16 to 2.21 Mcal/kg of NEm and 1.50 to 1.54 Mcal/kg of NEg among sources. In fact, many ruminant nutritionists prefer using corn DDGS instead of corn grain for finishing feedlot cattle because it contains 118 to 130 percent of the energy value of corn, and due to its low starch and readily fermentable content, feeding high amounts reduces the risk of rumen acidosis compared with feeding dry-rolled corn (Ahern et al., 2011).
Unfortunately, there are limited data on the energy content of reduced-oil DDGS for beef cattle. Bremer (2014) determined the energy value of reduced-oil (7.2 percent crude fat) and high-oil (12.0 percent crude fat) modified wet DDGS with solubles when fed at 20 or 40 percent of dry matter intake to growing calves and showed no difference in energy content between the reduced-oil and high-oil modified wet DDGS with solubles sources. They estimated the energy value of these two DDGS sources was about 124 percent of the energy value of corn grain. However, when these sources of modified DDGS with solubles were fed to finishing cattle, the reduced-oil DDGS source had about 89 percent of the feeding value of high-oil DDGS, but feeding the reduced-oil modified wet distillers source improved gain: feed with increasing diet inclusion rates. DDGS reduces acidosis Feeding diets containing DDGS reduces acidosis in feedlot cattle fed high-grain diets. Subacute acidosis is often a problem when finishing cattle are fed high-grain diets because corn grain contains a high amount of rapidly fermentable starch.
However, the starch content in DDGS is low (two to 5 percent), while the fiber, protein and fat content are relatively high allowing the amount of forage in the diet to be reduced when feeding diets containing more than 20 percent DDGS of dry matter intake. Furthermore, low-quality forages can be used effectively in diets that contain greater than 20 percent DDGS because of its high protein content (Klopfenstein et al., 2008).