Harvesttime mixing of wet distillers grains and corn silage may be the best way for some dairy producers to handle the ethanol byproduct, says Dave Schingoethe, a South Dakota State University dairy scientist.

Wet distillers grains stay fresh for only five to seven days, Schingoethe points out. For producers who can't feed them that fast, blending them with corn silage prevents spoilage, plus it simplifies daily ration mixing.

“We've had very good luck with just putting wet distillers grains in silo bags,” says Schingoethe. “But blending it with corn silage is one way to, from day one, make a little bit more-complete feed.”

He points out that wet distillers grains are about 30% protein on a dry matter basis, compared with roughly 8% for corn silage. So blends of the two products are much higher in protein than corn silage alone.

“You don't have to add a lot of other protein supplement, and in fact depending on what animals you're feeding it to, you might not have to add any protein supplement,” he says.

Increased stability at feed-out is another advantage. In South Dakota State research, corn silage-wet distillers blends fermented well, but with higher acetic acid levels than with corn silage-only fermentation.

Research at the University of Delaware showed that silage high in acetic acid remains stable longer after exposure to air than does straight corn silage, and the South Dakotans verified that finding. In their studies, corn silage began heating within 42 hours, but 75-25 and 50-50 blends of corn silage and wet distillers grains remained stable for 312 and 648 hours, respectively.

Watch the ration moisture level when feeding significant amounts of the blend, Schingoethe warns. Both feeds are high in moisture, so if the blend is fed as the only forage, intake may be limited. He and his co-workers encountered that problem when feeding high levels of wet distillers grains in research trials.

“Once we push up above 25-30% of the total ration dry matter as wet distillers grains, and if we've also got other wet feeds, such as corn silage, in there, then we see a tailing off of dry matter intake and milk production,” he says.

Another consideration: Both are corn-based feeds, so if the blend is the only protein source in a ration, the amino acid lysine could become limiting. That could cause a reduction in milk protein and, in more severe cases, a drop-off in milk production.

“But for most dairymen, if they're formulating at 16-18% crude protein on a dry matter basis in their diets, they're usually going to be adequate in protein — not a big excess — so they're probably not going to notice that possible deficiency,” says Schingoethe.

Blending the two feeds may be the best option for dairy producers who can get a big batch of wet distillers delivered at one time, and can mix them without slowing the corn silage harvest, says the dairy scientist. In bunker silos, he thinks delivering alternate loads of chopped corn and wet distillers, and mixing them with the packing tractor, would work.