Species-Specific, Process-Specific DDGS Nutrition Profiles Needed

How do low-oil, low-fiber, high-protein coproducts successfully find their best markets? This article appears n the May issue of EPM.
By Susanne Retka Schill | April 13, 2016

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.

Shurson still gets calls about the research he and Brian Kerr (USDA-ARS, Ames, Iowa) conducted a few years ago on the metabolizable energy value of DDGS for growing pigs with a range of oil content between 4.9 and 13.2 percent. “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. “If dealing with poultry, you’re really limited in the amount you can include of distillers because the utilizable energy has been reduced quite significantly,” he says, stressing the impact of low-oil DDGS in feed rations is species specific, and also will differ within species by stage of life.

High fat levels in dairy rations have been shown to reduce milkfat, for example, so some nutritionists argue that low-fat distillers should be beneficial. But the real issue, Garcia notes, is knowing the levels and effects of the different fatty acids. Oil content varies from plant to plant and, with distillers typically piled and not segregated by different qualities, it can vary between shipments from a plant. It can be difficult for the feeder to know the actual value. “You don’t usually analyze distillers grains,  because of the volumes going through the farm—by the time you test the shipment, you’re done with the feed.”

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.”

Now, the Nebraska team is trying to anticipate the changes coming with new technologies that will alter other components, such as the fiber and protein content. The 2016 Nebraska Beef Cattle Report shows the results of several feed trials attempting to isolate the contributions of solubles, protein, fat and fiber, compared to a diet of 40 percent wet distillers grains (WDGS) and a control diet of dry-rolled corn. There were significant improvements in both feedlot and carcass performance in the steers fed WDGS compared to dry-rolled corn, but none of the four DG components, alone, explained the energy value associated with wet distillers grains.

Erickson says feed trials like these are necessary to learn “what the cattle will tell us.” Earlier research, for example, found better results from beef cattle than initially expected, with wet cake worth 130 to 135 percent the value of corn in feed rations for feeder cattle, while DDGS are closer to 110 percent.

Protein Puzzle
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. “There is a poor relationship between lysine and crude protein content in corn, which remains when producing high protein DDG,” he says. “This means that we can’t assume that just because the protein content in DDG is increased, that it provides substantially more feeding value to pigs because the concentration of some of key amino acids does not increase proportionally.”

The situation is similar for poultry, Garcia says. A higher protein distillers grains product actually might have limited value because of the need to properly balance the amino acids. “The more distillers grains you use, the more deficient you will be in lysine, and the more you will have to supplement,” he says. Dairy and beef cattle, on the other hand, don’t require high protein. “I don’t see so much of a benefit from higher protein. It will all depend upon how much you pay for the amino acids you have to buy to balance the protein with.”

Erickson also says it is incorrect to claim higher protein levels always make a better feed. “I would argue the opposite for finishing cattle,” he says. “It doesn’t make it a better feed, it makes it a protein supplement.”

The protein equation demonstrates the challenge for an ethanol producer. “What’s good for swine or dairy isn’t always the best thing for beef cattle,” Erickson says. “It makes it very difficult, if you are a plant and marketing to all three, to make a blanket statement. It depends on which animal you are marketing the feed to.”

Another challenge facing the animal nutritionists is that the new batch of technologies being deployed in the ethanol industry is increasing the variability of distillers. “There’s no standardization of process at all,” Shurson says. “In fact, it’s becoming more diversified among plants.” Shurson says the ethanol industry needs to have good data in hand when introducing new coproducts to buyers.

Research Need
Two types of research trials are needed, Shurson says. One set of feed trials is needed to establish nutrients for accurate feed formulation. Swine researchers want to know the metabolizable energy value, digestible amino acid profile and phosphorus content to properly formulate a ration for the second round of feed trials that measure growth performance. “I want to make sure we’re not shorting the animals, which would provide bad results,” Shurson says. “And at the same time, I don’t want to be too conservative and underestimate digestible energy and nutrients because I would end up using more or not replacing as much as I could.” 

According to the three nutritionists, well-designed feed trials can cost between $50,000 and $100,000. Garcia says that because research funding is tight at universities, it is much harder today than in 2002 and 2003 when he started doing feed trials, and the distillers grains was low-cost. “Now it’s very difficult to obtain funding to do some basic research on distillers grains, even though we have new product.”

Erickson credits the generous support from the Nebraska Corn Board for Nebraska’s continued research. Without that funding, he estimates the university would likely be able to conduct one-tenth of the research. Likewise, Shurson credits the Minnesota Corn Research and Promotion Council and the National Pork Board for providing the majority of research funds for the studies he has conducted.
Besides having the data to find the best use with the right species for new coproduct iterations, there is another incentive for the ethanol industry and its supporters to conduct more nutritional research.

Shurson points out that ingredient values in the feed market were established on traditional nutritional measures that now are considered inaccurate for species like poultry and swine—things like total digestible nutrients, ash and crude protein, fat and fiber.

 Nutritionists now use more accurate nutritional values to calculate economical rations. Shurson has given several presentations to U.S. Grains Council audiences showing big value differences among DDGS samples from 144 sources when formulating swine diets. The value gap was greatest in swine grower-finisher diets, where the actual economic value using the metabolizable energy, digestible amino acids and phosphorus ranged between $195 and $289 per metric ton at a time when the value of DDGS in the spot market, which reflects the traditional pricing measures of crude protein, fat and fiber, was $182 per metric ton.

It will take time for market prices to reflect real nutritional value. In the meantime, ethanol producers introducing new or altered coproducts will be well-served by getting the right data to help the new feeds find the right market. 

Author: Susanne Retka Schill
Managing Editor, Ethanol Producer Magazine