Wet and distiller’s dried grains with solubles (DDGS) have become a popular, economical, partial replacement for corn and soybean meal in animal feeds, according to Jerry Shurson, an animal nutritionist with the University of Minnesota Extension. A total of 207 ethanol production facilities in the United States produce more than 36 million metric tons (39.6 million tons).
DDGS is the main ethanol co-product fed to swine; its energy value is nearly equivalent to corn even though most of the starch is removed to produce ethanol, he explains.
“This is due to the fact that all other nutrients, including corn oil, remaining in the co-product after ethanol distillation, are concentrated by a factor of three,” Shurson says. “Corn oil has a much higher (about 2.25 times) energy value compared to starch, and is the main reason why DDGS is considered such a valuable energy ingredient in swine feeds.
“However, due to the high price of crude corn oil and the relatively low capital investment required by ethanol plants to install centrifuges to extract some of the corn oil prior to making DDGS, the profitability and return on investment of oil extraction from the ethanol co-product stream is high.”
This has led the ethanol industry to extract more oil before making DDGS. In turn, reduced-oil DDGS has produced a lot of anxiety in the feed, livestock and poultry industries because of the removal of some of the energy value of DDGS, Shurson says.
To determine just how much change in DDGS composition is occurring, Shurson teamed up with Brian Kerr of USDA’s Agricultural Research Service in Ames, IA, to study the impact of oil extraction on energy content for pigs using 11 different DDGS sources. The project was funded by the Minnesota Corn Research and Promotion Council and the U.S. Department of Agriculture. Cenex Harvest States assisted in providing DDGS samples for the project.
Project researchers determined that the change in oil content of DDGS had much less of an effect on energy value than the change in fiber content.
“This was initially surprising because of the high amount of calories in corn oil compared to the calorie concentration in corn fiber,” Shurson points out. “In fact, many people were expecting a simple answer, such as ‘removing 1 percentage unit of corn oil reduces energy value by x-number of calories. But this relationship does not hold true because of the variable concentrations of other nutritional components that either contribute to increased energy or reduce the energy value.”
From this research, Shurson and Kerr developed accurate energy prediction equations to provide nutritionists, pork producers and DDGS marketers the tools needed to determine changes in energy value of any source of DDGS, and negotiate price based on changes in energy value.
For more information about DDGS, go to www.ddgs.umn.edu.