Species-Specific, Process-Specific DDGS Nutrition Profiles Needed

by Susanne Retka Schill (Ethanol Producer Magazine) How do low-oil, low-fiber, high-protein coproducts successfully find their best markets? -- An array of distillers grains coproducts are entering the market—low oil, low fiber, high protein—with great potential. But animal nutritionists caution that finding the best and right market for the modified coproducts isn’t as simple as it’s sometime made out to be.

“They’re all great coproducts, but very little R&D has gone into understanding what their feeding value is going to be,” says Gerald Shurson, a University of Minnesota swine nutritionist in St. Paul. “For some companies, it’s the commodity mentality—we’ll make it and they will buy it. And that’s not how it works.”

There’s room for more distillers grains in animal diets, says Alvaro Garcia, dairy nutritionist at South Dakota State University in Brookings, “but we have to be careful with products we put into the market. It takes so much work for some markets to accept distillers grains,” he says, adding that one bad shipment can destroy a market, particularly in new export markets.

Galen Erickson, beef nutritionist at the University of Nebraska in Lincoln, points to the rapid adoption of corn oil extraction. “I think that shined a negative light on the industry because ethanol producers went ahead and did it, and really didn’t have any values determined on what the impact would be on the feeding side. That’s gotten people anxious about any other changes that come along.”

It is evident from discussions with the three animal nutritionists about what they have learned in their research on the changing coproducts that the impact varies by species.

“Oil content, surprisingly, is a poor predictor of energy value in DDGS,” Shurson says. Follow-up trials verified growth performance is not affected when feeding 40 percent DDGS diets containing 6, 10 or 14 percent crude fat containing similar metabolizable energy content.

Garcia explains that in dairy rations, DDGS primarily contribute energy and protein. Reducing fat content means less energy. The difference with swine may result from the pig’s ability to extract some energy from the DDGS fiber in the digestive tract, he suggests, a function shared with dairy but not poultry.

The team at Nebraska has studied low-oil distillers effect in cattle rations. “It has decreased the energy value some and there’s a lot of debate on what that number should be,” Erickson says. In the past four years, the first samples tested had little impact on feeding value. “More recently, the more aggressive they seem to get [in removing oil], the bigger the impact. We’ve tried to stay ahead of that.”

The complexities in establishing nutritional value get even knottier when examining protein. Many assume that higher protein distillers grains will be a welcome improvement, particularly because protein often is a higher priced feed component. But the animal nutritionists caution it is not that simple.

Shurson points out swine nutritionists want to know digestible amino acid levels.

Two types of research trials are needed, Shurson says. One set of feed trials is needed to establish nutrients for accurate feed formulation.