If concern about mold and spoilage of wet distillers grains (WDG) has limited your use of this nutrient-rich byproduct of the ethanol industry, it may be time to give it another look.
University of Nebraska ruminant nutritionist Aaron Stalker acknowledges that the caveat with this high-moisture feed has been storage and the fact that WDGs begin to spoil after about 10 days. But Stalker, based at the West Central Research and Extension Center in North Platte, reports he and his Nebraska colleagues are finding that successfully storing and feeding WDGs can be quite simple.
Moreover, as corn price continues to soar, Stalker says savvy feeders and cow-calf producers need to look at such byproducts as an economical feed alternative. Likewise, because dried distillers grains (DDG) tend to be more expensive due to the extra energy cost of drying, Stalker says feeding WDGs offers a cost-cutting opportunity.
That said, presently most of the demand for WDGs is in winter, when more cattle are on feed and it can be fed before spoiling, explains Stalker. But this demand also makes WDGs more expensive to buy during the winter months.
Instead, he says, “Producers need to buy WDGs in the summer when it's cheap and store it to use as winter feed.”
Stalker has experimented with storing WDGs in several different scenarios at the Gudmundsen Sandhills Laboratory (GSL), a working Nebraska research ranch near Whitman. In all instances, he reports the feed lost minimal nutrient quality — if any — and was safe to feed to livestock.
The lowest-cost trial entailed dumping WDGs on the ground in late July. By October, it had formed a moldy crust about 4-in. deep, but Stalker says, “Beneath that, the WDGs looked as golden as the day they were delivered.”
A nutrient analysis on the feedstuff found the WDGs were 32% protein at delivery in July, and remained the same in an October test. Even the crust was 32% protein.
Regarding the mold in the crust, Stalker says analysis showed it was mostly yeast, and the molds that produce aflatoxin and other mycotoxins weren't present.
“The WDGs — crust and all — were fed to gestating cows and calves in the feedlot with no health or performance problems,” he says.
Similar to ground storage, another low-cost alternative is to make a U-shaped bunker with large round bales, line it with plastic, and unload the WDGs. Then cover the top with plastic weighed down by tires. Stalker used this method on product delivered in early September, and reports that while some mold formed in the feed's top layer, it wasn't as deep as the open storage and did no harm to the feed. “It may look spoiled, but the cows will eat it,” he says.
Stalker also stored WDGs in a cement bunker covered with plastic weighed down with tires. In this scenario, there was no mold at all. The amount of mold appears to be related to the oxygen permeability of the plastic. Stalker's observation is: “Thicker plastic reduces the mold layer.”
As an alternative to the plastic, Stalker tried ground wheat straw or other forage for the top layer. While there tends to be a dark discoloration where the straw and WDGs meet, Stalker says the cattle still will eat the feed. As a personal preference, Stalker says, “I like using the plastic better.”
Nebraska researchers and the University of Illinois are also evaluating topping stored WDGs with a layer of salt. Initial results from Illinois suggest it may have merit.
Nebraska beef nutritionist Terry Klopfenstein and feedlot specialist Galen Erickson are also looking at mixing WDGs with wheat straw, grass hay and alfalfa. They've found mixing the wet product with forage in a mixer wagon and putting it into a bag or silo makes handling easier and appears to keep the feed indefinitely. These mixtures can also be stored successfully in a cement or temporary bale bunker, but do require packing and should also be covered with plastic.
In a bunker, Stalker says research suggests inclusion of the forage at the following percentages on a dry matter basis: grass hay 30-40%, wheat straw 25-32% or alfalfa hay 45-55%. If bagging the mixture, those percentages should be decreased to: grass hay 15%, wheat straw 12.5% or alfalfa hay 22.5%. A 50-50 mix of WDGs and DDGs can also work when bagging the feed.
Stalker says the primary caution in using a bag is to avoid too much pressure, which can cause the bag to blowout. When filled with the WDG-forage mix, the bags are about 6-ft. tall and 6-ft. wide.
When it comes to feeding, Stalker and his colleagues have found the feed — whether straight WDGs stored in a pile or mixed with a forage — can easily be delivered to cattle through a feed wagon. On range and pasture settings, he's been feeding WDGs on the ground and says the cows leave very little waste.
To evaluate animal performance, Stalker is conducting a comparison trial at GSL this winter between cows fed WDGs on the ground vs. those fed via bunk. His early observations indicate little difference in animal performance.
All totaled, Stalker believes that with many of the storage issues resolved, there are many opportunities ahead for cow-calf operators to integrate WDGs into their feeding programs. He suggests using stored WDGs for young growing animals, replacement females, wintering the cow herd or cows needing extra supplement six to eight weeks after calving when lactation peaks.
He cautions that transportation costs still need to be feasible for getting the feed. But when the price is right, Stalker says such products are a good idea because they're high in energy, protein and phosphorus, which is often deficient in forage-based diets. They are “nutritionally excellent for beef cows,” he adds.
Kindra Gordon is a freelance writer based in Whitewood, SD.
No mycotoxin worry
In his recent studies of wet distillers grains (WDGs) stored through the summer and fed during the winter, Aaron Stalker analyzed samples from four different storage sites for mycotoxin concentrations. The University of Nebraska ruminant nutritionist reports all samples were found to be safe.
His analysis tested for the presence of aflatoxins, ochratoxins, vomitoxin, zeralenol, zearalenone, T-2 toxin and fumonisin — all the major mycotoxins found in grains and grain by-product feeds. Stalker reports only fumonisin was found to be present in all four samples — but at a low, safe level.
The site with the greatest concentration of fumonisin was 1.4 ppm, with the average in all four samples being 0.8 ppm. “The FDA recommends levels of total fumonisins in rations for beef cattle not to exceed 30 ppm, so these levels are considered safe. For comparison, the FDA considers 3 ppm the safe threshold for human foods,” he adds.
Because the fresh WDGs weren't tested, Stalker says it's possible the fumonisins were in the corn grain, ended up in the WDGs at the ethanol plant and aren't storage related.
The bottom line is that mycotoxins are of minimal concern and storage of WDGs is a viable option, he concludes.
Aaron Stalker, University of Nebraska ruminant nutritionist, offers these tips:
Distillers grains (DGs) tend to be high in fat, which can decrease fiber digestion. The common feeding rule is to not exceed 5% fat in the diet. Thus, DGs shouldn't make up more than 50% of the diet provided there are no other fat sources in the diet.
DGs can also be high in sulfur, which can cause polio or “brainers.” The maximum tolerable limit of sulfur in a cow's diet is 0.4%. By keeping DGs at 50% or less inclusion in the diet, a high sulfur risk should be avoided provided there are no other sulfur sources in the diet. Supplementing thiamin, a B vitamin, can also minimize the risk. Water is often a source of dietary sulfur and should be tested for sulfate levels when feeding high levels of DGs.
Because DGs are high in phosphorus, supplemental calcium may be needed to balance the calcium:phosphorus ratio. A 2:1 ratio is necessary to minimize the risk of water belly.
Because of the potential for a wide variability among DGs — even from the same plant on the same day — have a nutrient analysis done to ascertain the quality and any nutrient concerns.