For ethanol plants, drying distillers’ grains for feed represents a significant investment -— as much as 50 percent of their natural gas usage, according to Iowa State University beef specialist Dan Loy, PhD. Consequently, the plants prefer to market the product as wet distillers’ grains at 25 to 35 percent dry matter and will sell it at a much lower price. Shipping costs limit the distance for cost-effective transport, but for beef producers located close to ethanol plants WDG becomes price-competitive as a protein and energy source. The biggest challenge, Loy says, is storage of the perishable product.
Stored in the open, WDG will spoil and mold quickly, but Loy says producers and researchers have experimented with methods that successfully extend the storage life of WDG. University studies, he says, show that wet distillers’ grains won’t ferment in storage like silage, because fermentable carbohydrates are fermented out in ethanol production. The product does, however, become stable in the absence of oxygen. Successful storage systems include bagging and covering small piles of modifi ed wet distillers’ grains, at 50 to 55 percent dry matter, with plastic. Another strategy is to mix WDG with 10 to 20 percent dry forage, as fed, to produce a 60 percent moisture mixture that can be packed into silos or silo bags. Loy says layering of forage and wet distillers’ grains into a bunker silo can also be a successful strategy. Research at Iowa State has found storage losses to be 7 to 12 percent, with cost per ton as low as $5, using these techniques.