In fact, the concentration of neutral detergent fiber (NDF) in DDGS compares similarly with other ingredients such as alfalfa hay and other nonforage fiber sources (Figure 1). However, the industry often fails to recognize the value of this fiber.
To facilitate discussion about the value of fiber in DDGS, we need to first provide background on the ethanol process. In order to produce ethanol, biorefineries simply remove starch from corn or other grains and then use yeasts to ferment the starch and soluble carbohydrates to ethanol. All remaining components from the corn passes through to the DDGS and gets concentrated because of the removal of starch.
In order to get an efficient removal of the starch, biorefineries need to grind the corn or grain so that yeasts and enzymes can access the starch. Because of this step, the resulting DDGS has a small particle size. This smaller particle size creates questions for nutritionists and producers about how well DDGS promotes rumen health and stimulates cud chewing.
The industry does have several ways of measuring effectiveness of fiber. Calculations such as effective NDF, physically effective NDF, physically adjusted NDF and undigested NDF all try to characterize nutritional value of fiber. While these estimates do provide a useful tool for formulating diets, they still can’t capture the actual effectiveness of fiber. Factors such as environmental conditions, digestibility and dietary ingredients can all affect the actual value of fiber to the animal.
Research
In order to address some of the questions related to this topic, researchers at the University of Nebraska recently conducted a study in which they fed lactating Jersey cows a series of diets with different fiber sources. On a dry mater basis, the treatments included: (1) a control diet with 18.2% alfalfa hay, 0% DDGS, 0% straw (2) 12.1% alfalfa hay, 6% DDGS, 2.1% straw (3) 6.1% alfalfa hay, 12.1% DDGS, 4.2% straw and (4) 0% alfalfa hay, 18.1% DDGS, and 6.2% straw. Formulations included different amounts of Soypass and corn to balance for similar metabolized-energy- and metabolized-protein-predicted milk across all treatments.
Researchers presented the results of this study at the 2019 ADSA annual meeting. Cows consumed similar amounts of feed and had similar energy-corrected milk production across all treatments (Figure 2). Furthermore, treatment did not affect yield of fat or protein (Figure 3). However, researchers did observe a quadratic trend for greater amounts of energy-corrected milk and fat yield from cows fed the diets containing 6% and 12.1% DDGS compared with cows fed the other diets. Researchers also observed a linear decrease in water intake and methane production from cows fed the higher distillers diets.
Implications for the industry
Most dairy producers and nutritionists would probably agree that purchasing high-quality forages represents a key challenge for dairy operations. Issues such as nutritional variability, shipping and shrink, and economics all contribute to this challenge.
Variability
Conditions such as growing environment, harvest time and alfalfa variety cause the nutritional value of alfalfa to vary. Cows love consistency. When the nutritional value of alfalfa varies from load to load or from field to field, we often see negative effects on performance. This variability also forces nutritionists to make additional formulation changes.
Although DDGS have some variability, the differences tend to occur more between biorefineries rather than within a specific biorefinery. Processes and conditions used during ethanol production affect DDGS quality, and as a result, sourcing from a single ethanol producer reduces the variability that we see in quality of DDGS.
Finally, characteristics such as digestibility can vary considerably with alfalfa or other forages. We may see fewer differences in digestibility of distillers from the same biorefinery.
Shipping and shrink
Hauling forages requires additional labor and equipment compared with transporting a grain commodity. Furthermore, depending on the individual situation, the dairy may need to process the hay prior to feeding which could lead to additional shrink.
Economics
Feeding DDGS typically provides significant feed cost savings for producers. Although the actual benefit changes depending on prices, region and availability of other ingredients, we can still make comparisons to demonstrate the value. If we use typical Upper Midwest values for all the ingredients, including DDGS in the diet reduced feed costs by $0.11, $0.22 and $0.37 per head per day for the low-, medium- and high-DDGS diets. If we also consider changes in milk production, the DDGS diets improved income over feed cost by $0.32, $0.51 and $0.17 per head per day compared with the control diet.
In conclusion, this research shows how DDGS can provide dairy producers and nutritionists with options during periods of high alfalfa price or low alfalfa availability. This year’s growing conditions will likely create challenges for producers trying to source high-quality alfalfa hay. Feeding DDGS along with a lower quality and cheaper source of fiber could offer advantages by reducing feed costs while still meeting the fiber requirements of the dairy cow. 
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Kevin Herrick
- Technical Service Director of Nutrition
- Poet Nutrition
- Email Kevin Herrick
