Marshall, Minn. — It’s not often that removing a key ingredient makes a recipe better, but reducing oil in distiller’s grains may improve swine diets as well as ethanol-plant profits, according to a recent study.
Dry-mill ethanol plants generate thousands of tons of granular leftover — distiller’s grains — each year. The ethanol fermentation process also yields fat-containing syrup, called solubles, which are usually sprayed on distiller’s grains and dried. The result: distiller’s dried grains with solubles, or DDGS, which are typically used as a feed ingredient in dairy, beef, poultry and swine diets.
Sometimes the syrup is not put back onto dried grains. For example, the Corn Plus ethanol plant in Winnebago combusts solubles for energy to reduce natural-gas use. Otter Tail Ag Enterprises of Fergus Falls has evaluated anaerobic digestion of the stillage to produce methane gas for thermal energy. Other ethanol plants are considering simply extracting the oil. All these processes result in a lower-oil feed ingredient that is showing promise for Minnesota’s hog industry.
A study of distiller’s grains in finishing hog diets, by a University of Minnesota research center in Waseca, proved that including 20 percent low-soluble grains in hog diets did nothinder growth or affect pork quality. In fact, the hogs were leaner with a better gain-tofeed ratio. Also, protein in the low-oil DDGS feed was easier for the animals to digest.
“The standard, higher-oil DDGS had negative impacts on the pork-carcass characteristics and pork-fat quality,” says Dennis Timmerman, AURI project director. “We were looking at lower-oil distiller’s grains to possibly alleviate those challenges.
But the value may extend beyond the pork industry to ethanol plants, which use the extracted oil for additional revenue. For example, biodiesel could be produced from the oil and used to reduce a plant’s fossil-fuel use.
Plants can determine the best use for the oil, “without affecting the net value of the DDGS to swine producers,” Timmerman adds. “In fact it may be an improvement.”