There is something monumental underway. No question, ethanol production is going to impact your business. You’ve already felt the pinch of rising corn prices, and it started during harvest season. When was the last time that happened?
Well, get used to it. There’s a long climb ahead of you in the next several years as ethanol producers, livestock producers and other corn customers struggle to find a balance. Sure, the path will smooth out at some point in the future, as corn genetics, acreage adjustments and ethanol processing find ways to refine the tools of the trade.
For your part, if you don’t know much about distillers’ dried grains with solubles — a corn ethanol byproduct — you need to become familiar because there will be a mountain of product. There’s plenty of information to sort through, although much of it is evolving as research uncovers new answers.
Before you think about mixing DDGS into your swine rations, you need to understand what constitutes a quality DDGS product and what to look for in a supplier.
Start with a nutrient profile
DDGS sources vary in terms of nutrient concentrations. But an average product contains about 28 percent crude protein, 10 percent fat, 7 percent crude fiber and 0.7 percent phosphorus. (See sidebar for ranges.)
“The amino acid concentration is approximately three times greater than in corn; the same goes for fiber,” says Hans Stein, University of Illinois swine nutritionist.
Lysine is a key factor to watch in DDGS. It’s more variable than other amino acids because overheating causes it to bind tightly to carbohydrates and it and reduces its digestibility. “If the lysine concentration is less than 2.8 percent of the total crude-protein concentration, then the product is likely heat damaged to the point that it’s undesirable for swine feeding,” Stein says.
Producers should analyze the product’s lysine and crude protein levels, he notes. Then calculate the lysine as a percentage of total crude protein to ensure that minimal heat damage has occurred. Even without heat damage, dietary lysine levels in DDGS are lower than in corn or soybean meal. This means that crystalline lysine needs to be added to balance the diet. DDGS has a high digestible-phosphorus content, so less inorganic phosphorus would be needed.
DDGS’ energy level is similar to corn, but there is more fiber. Neither should affect pig performance, Stein says.
Diets will need to be formulated based on digestible-amino-acid and phosphorus levels. “As a rule of thumb, for each 10 percent of DDGS that is included in the diet, you can remove about 5.80 percent corn, 4.20 percent soybean meal and 0.2 percent monocalcium phosphate,” he adds. “At the same time, you need to increase the inclusion of crystalline lysine and limestone by 0.1 percent.” With those factors in place, DDGS usually does not affect pig performance.
Not all DDGS is created equal
Of course, you can expect DDGS nutrient levels to vary between sources, but complicating the prospect is the fact that it also can vary over time within a plant.
“Much of the variation in nutrient content of corn DDGS is likely due to normal variation among crop varieties and where it is grown,” says Jerry Shurson, University of Minnesota swine nutritionist.
For the raw grain itself, some influencing factors include grain type and variety; grain quality, which is influenced by soil conditions, fertilizer, weather, production and harvesting methods; and the grain formula.
On the processing side, the list is huge. “As nutrients in DDGS become concentrated due to starch fermentation to produce ethanol, it’s no surprise that nutrient variability among DDGS sources also widens,” Shurson says.
In addition, the ratio of condensed distillers’ solubles that is blended with distillers’ grain to produce DDGS varies between plants. “Because nutrition composition between these two fractions differs greatly, it’s understandable that the proportions would significantly effect the DDGS’ final nutrient composition,” Shurson notes. Some ethanol plants add all of the condensed solubles produced into the grains portion before drying, while others add much less.
The process to make ethanol from corn varies from plant to plant. In some cases, the processor’s objective is to find a product niche or technology that gives the refinery a competitive advantage. Depending on the plant, the distiller's byproduct may have have less nutritional and economic value than DDGS.
“Processing at the ethanol plant is the largest influencing factor on DDGS quality,” Shurson says. Such factors include the grind of the corn (the finer, the lower the value), cooking, fermentation and drying (dryers can vary from 260° F to 1,200° F). He offers a look at some of the ethanol refining processes that can affect the DDGS product.
Some plants use cookers to add heat for fermentation and use less enzymes. Other plants use more enzymes and don’t rely on cookers as much for fermentation. “Theoretically, using less heat could improve amino-acid digestibility of DDGS, but there haven’t been any studies on this,” Shurson says.
Some plants partially de-germ the corn before fermentation. This reduces the fat and energy levels in the final DDGS.
Some plants market wet distillers’ grains, which results in high levels of solubles added to the grain to produce DDGS. “This creates a DDGS product with a higher fat level,” he notes.
One company produces a pelleted DDGS product (mostly for export). But to make a quality pellet, 20 percent soybean hulls are blended with the DDGS. The soybean hulls increase the fiber content and dilute all of the other nutrient levels.
Whisky distillers produce a slightly different DDGS than ethanol refining because of the grain mixture used.
There are examples of products labeled as DDGS, which are actually corn gluten byproducts or blends of other distillers’ byproducts, Shurson notes. To distinguish between these types of products and corn DDGS, he suggests checking the fat and phosphorus content. Corn DDGS is higher in both.
In terms of quality, it’s worth noting that ethanol refining does not destroy mycotoxins present in the grain. Actually, by the time DDGS is produced, the concentration levels increase by three fold. “Many ethanol plants screen the grain prior to accepting it. If a pork producer is looking to buy DDGS, he should get the supplier’s assurance that an acceptable mycotoxin quality-control plan is in place,” Stein says. You also can send DDGS samples to a commercial lab that uses HPLC procedures for mycotoxin detection.
Look for the golden glow
So, how do you ensure DDGS quality?
There are no standards set for DDGS composition, nor is there a grading system to help differentiate quality.
For now, color is the best indicator you have to measure DDGS quality. However, color can range from dark, burnish gold, almost brown to a light golden hue. Because excessive temperatures darken DDGS, go for the gold. Focus on the lightness and yellowness — that appears to be a reasonable predictor of digestible lysine content.
“Even then, true lysine-digestibility coefficients for swine ranged from 44 percent to 63 percent,” Shurson notes.
There is some price differentiation surfacing based on subjective color scores. In fact, it’s not uncommon to find a $10- to $15-per-ton price difference between “golden” DDGS and darker-colored versions.
“You’re going to have to take control,” Shurson says. “It’s important to identify specific ethanol plants that produce the type of DDGS with a nutrient profile and color that best matches the feeding application,” Shurson says.
One place where you can find help is www.ddgs.umn.edu; look under the “Nutrient Profile” section.
“There has been considerable discussion about standardization, but little interest,” Shurson says. National committees are evaluating the prospect of DDGS nutrient standards and product testing procedures.
Realistically, he doesn’t see standardization happening on an industry-wide basis but perhaps within companies, cooperatives or regions. “Most ethanol plants are very secretive; they don’t want to tell you about their processes,” Shurson says. “But some plants are getting serious about DDGS.”
Getting serious about incorporating DDGS into your swine rations may be a bit of an up-hill climb. But research and other producers’ experiences will continue to provide answers. Besides, scaling the DDGS mountain is one way to offset some of the rising corn prices that you will face, at least until the market reaches a new balance.
Finding a Home within the Range
If you’re going to include distillers’ dried grains with solubles in your swine rations, it has to carry its weight in nutrients. But accomplishing that task consistently is a challenge. Hopefully some refineries will commit to standardizing DDGS byproduct quality.
Here’s a look at 32 U.S. corn DDGS sources and the nutrient ranges that they present.
Crude Protein 28.7% - 32.9%
Crude Fat 8.8% - 12.4%
Crude Fiber 5.4% - 10.4%
Ash 3.0% - 9.8%
Calculated ME 3,504 – 4,048 (swine) kcal/kg
Lysine 0.61% - 1.06%
Arginine 1.01% - 1.48%
Tryptophan 0.18% - 0.28%
Methionine 0.54% - 0.76%
Phosphorus 0.42% - 0.99%
Source: University of Minnesota