Bunker Storage

While storing straight WDGS or adding forage with WDGS and storing in bags may fit for many producers, others have wanted to bring in quantities that make bagging difficult, or the producers may have a bunker to store feed. Storing WDGS in bunkers is somewhat different than in bags. However, the concept is still the same in terms of adding feeds to WDGS to ensure that when the mixture is packed into the bunker that air is excluded. The amount of forages needed has been evaluated and many producers have adopted this practice successfully.

We initially mixed 30% grass hay with 70% WDGS (DM basis) and packed with a skid loader with rubber tracks. This mixture worked fine and compacted; however, the weight of a pay loader was not maintained on the pile. A bunker with 40% grass hay with 60% WDGS (DM basis) did compact in the bunker and yet maintained the weight of a pay loader (Figure 7). Similar to bagging, forage sources can likely be exchanged on an equal fiber (i.e., NDF) basis. For example, 29% corn stalks was successfully stored with 71% WDGS in a bunker with little spoilage. In this example, dry cows were fed this mixture in a dry lot situation.

Many producers have made mixtures and packed them into bunkers. In some cases, these producers "made" bunkers with round bales or other less permanent structures. In all cases that we are aware of, producers had good experiences, were satisfied with their storage, and many have continued to store WDGS across multiple years. Many producers have recorded what the mixtures were on an as-is basis, and not always on a DM basis. We can make some estimates of the mixtures on a DM basis by using assumed moisture contents of the different feeds. When possible, we will report what is known (as-is percentages) and approximate the mixtures on a DM basis.

Figure 8 and Figure 9 are a mixture of WDGS and wheat straw from a cow-calf producer near Kearney, Neb. The mixtures used were 20% wheat straw and 80% WDGS (as-is basis) for both years. Assuming the WDGS is 35% DM and the wheat straw is 90% DM, this equates to approximately a ratio of 39% wheat straw and 61% WDGS on a DM basis. In year 1 (Figure 8), the pile was covered and bales were used for sides. In year 2 (Figure 9), the pile was larger and, again, covered in plastic with bales used for sides.

Modified WDGS is a dryer product than traditional WDGS. Therefore, less forage may be needed to adequately pack into a bunker. Figure 10 illustrates a mix of 15% grass hay and 85% MWDGS put into a bunker with round bales as sides. In many situations, mixing of the forage with WDGS is one of the biggest challenges.

First, the forages need to be ground or at least a sufficient particle size to adequately mix with WDGS. Often, producers may want to mix the forage and WDGS (or MWDGS) in a mixer that is used for feeding. However, if ranchers or producers do not have equipment for mixing, then mixing equipment can be rented or purchased or another system of mixing may be used. In Figure 11, this same producer that used MWDGS and grass hay used a front loader to mix the forage and MWDGS together during the packing process. Having an accurate mix with a known and consistent amount of forage may be more critical for feedlots than in many cow-calf situations. This method of mixing seemed to work fine for this producer. However, caution is required to ensure that there are no pockets of air due to inadequate mixing of forage and WDGS (or MWDGS) to ensure that spoilage does not occur. The same caution is required if particle size of the forage is not small enough to mix well with the WDGS.

For many producers, the task of mixing and storing WDGS or MWDGS may seem daunting. However, large quantities of WDGS can be stored and in a relatively short period of time if the WDGS can be procured. For example, in Figure 12, a Nebraska feedlot stored 9,000 tons at two separate locations in a concrete bunker. In this case, the producer was mixing everything through vertical mixers and was able to put up to 35 semi-loads of WDGS in the bunker a day for multiple days. The mixture used was 15% wheat straw (1-in. grind) and 85% WDGS (as-is basis). This equates to approximately 30% wheat straw and 70% WDGS on a DM basis, assuming that WDGS is 65% moisture (35% DM) and wheat straw is 90% DM.

One of the challenges with traditional WDGS (30-35% DM) is that it will not pile or allow for producers to make a bunker of straight WDGS with no added forage. Once the WDGS is piled, it tends to flow some and spread resulting in piles that are very wide, yet very short in height. For storage of relatively small quantities (1 semi-load of 30 tons or less), then storage may be accomplished by unloading WDGS directly onto plastic (Figure 13) and covering just after unloading (Figure 14). As illustrated in the picture, the piles are unable to be compacted with equipment, but spoilage is likely minimized. Figure 15 illustrates that some spoilage occurs on the surface, but little observed below the surface when piles are covered.

Modified WDGS that is 42-50% DM and WCGF that is either 45% or 60% DM does pile and may be stored in a bunker by itself without forage added. However, the pile cannot be compacted by driving equipment onto the feed in a bunker. There are numerous examples of producers that have piled and covered either WCGF or MWDGS and had little spoilage (except on the top surface as would be expected). In Figure 16, piling of MWDGS appears to work in either earthen bunkers or concrete bunkers. We would always recommend covering with plastic or some mechanism to minimize spoilage at the surface. This storage method of just piling either MWDGS or WCGF is "riskier" in terms of spoilage losses, but has been done at least commercially. If plants do not add solubles (corn syrup) back onto wet distillers grains to make WDGS, often times the WDG (without solubles) may pile easier than if solubles are added back to the wet grains. In Figure 17, a producer has piled WDG (without solubles) and covered the surface with stock salt (1 lb. per square foot at the surface) and plastic. The pile did not spoil and was fed throughout the winter following storage.

For more information or to request additional copies of this manual, contact the Nebraska Corn Board at 1-800-632-6761 or e-mail kelly.brunkhorst@nebraska.gov

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Date published: May, 2008