Distillers grain is an economical source of both protein and energy, points out Alvaro Garcia, South Dakota State University extension dairy specialist.

For harvesttime mixing with chopped forage, he sees corn silage as a better match for distillers grain than alfalfa haylage.

“The beauty of the mixture is you have low crude protein in corn silage and high protein in distillers,” says Garcia. “The problem in using distillers grain with haylage is you have high protein in both. So you end up with a product that's really high in protein.”

You might have to add minerals and perhaps a long-stemmed forage. But distillers grain plus a chopped forage is almost a complete feed, he adds.

Typically, more dry distillers grain is available from ethanol plants than wet, but either can be used. They're usually priced comparably on a dry matter basis, says Garcia. Currently, dry distillers costs $75-80/ton in South Dakota, and the wet form brings about a third as much.

When mixing wet distillers with chopped forage, you might need to chop the corn or alfalfa a bit drier so the mixture ends up at the right moisture content for ensiling. Also, watch the ration moisture level.

“If you have too many wet feeds, like corn silage, haylage and wet distillers grain, you might have too much moisture,” Garcia warns. “That might limit intake.”

When deciding how much of the ethanol byproduct to include in the mixture, keep in mind that too much of it can hurt milk production.

“South Dakota State University's research last year showed that milk production decreases when you go beyond 20% of the total dry matter in the diet,” Garcia reports. “So for a cow eating 50 lbs, 10 lbs would be tops. Usually, I don't feel comfortable feeding more than 6 lbs of distillers grain dry matter/cow/day.”

Heifers can be fed more. With dairyman Greg Moes, Garcia is evaluating a complete-ration mixture of wet distillers grain and shredded cornstalks for heifers. Moes recently began feeding the silage.

“We're trying to develop a very inexpensive feed,” Garcia reports. “We might have to include some straw to lower the crude protein and energy content a little bit more.”