If you've never fed distillers grains,high corn costs make this a good year to consider it, says David Schingoethe, South Dakota State University (SDSU) dairy scientist. Feeding distillers grains as 20% of a lactating cow's diet can increase milk production by 5-9% and be a lower-cost grain option, he says.

“One can easily go up to 20% of the ration as distillers grains, either wet or dried. We've got data supporting that you can go higher than that, too,” says Schingoethe. He and his colleagues have done extensive research on the byproduct that comes mainly from ethanol plants.

“If you go up to 20% distillers grains, somewhat depending on the quality of your hay or silage, you're in a situation where you can replace virtually all of the other protein supplements,” he says. “You could replace 85-90% of the soybean meal and 25% of the corn that you'd normally need.”

Distillers grains replace the starch from corn or other grains with a “readily digestible fiber source” and about 10% fat. That makes the byproduct higher in net energy lactation than corn.

“It's a fairly digestible feed but less apt to cause acidosis and digestive upsets than a high-starch diet.” Nebraska research on feedlot cattle fed 40-50% of dry matter as distillers found fewer liver abscesses and fewer cases of cattle going off feed, Schingoethe reports.

Distillers grains also contain“fairly unsaturated fats” that are less likely than vegetable oils to interfere with digestibility in the rumen.

“You also have the possible advantage of making a healthier milk” than with corn, Schingoethe says. Studies on fatty acid composition of milk from diets with 10% and 20% distillers showed a modest increase in conjugated linoleic acid (CLA), which can help fight cancer and other health problems in humans.

The studies also showed a production increase with both wet and dry distillers, ranging from 5% to 9%. “They tended to produce a little bit more with the wet product than with the dried,” he says.

But there are cautions to take, Schingoethe says.

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One is to consider how wet the diet will be. “If you have wet distillers grains and you also have a fair amount of corn silage or other wet feeds, you start getting too wet a diet.” That causes gut-fill that may limit intake, he says.

Some producers tell Schingoethe that they can't add much distillers to rations because, when they do, their milk fat tests go down.

“The problem probably is that the distillers grains are at about 38-40% NDF. Dairy nutritionists and producers look at the analyses and say, ‘I've got plenty of NDF in the diet; I can cut back on the alfalfa hay.’ Then, all of a sudden, the fat test goes down.” The lack of effective fiber — not the addition of distillers — caused fat scores to lower, he says.

Although lower alfalfa yields and higher hay prices have forced producers to look at other fiber sources, make sure at least 50% of the lactating cow's diet is forage dry matter, warns Schingoethe. SDSU studies showed “a nice linear decrease in fat test” when forage dry matter went from 55% to 35-40%. Wisconsin research brought lower milk fat numbers on a 45% forage dry matter diet.

Before adding distillers to a ration, know what's in them. Newer ethanol plants, Schingoethe says, aren't always putting out a consistent product. So if a nutrient analysis isn't available, have one done, he says.

“Some ethanol plants are trying new technologies where they might start pulling off some of the fat to see if they can make biodiesel or something like that.”

That lowers the energy of the distillers grains and raises the protein content, which can be an advantage. “But if you're guaranteeing 30%protein and providing 33%, I, as a dairyman, could have saved some money by reformulating.”

Some plants, he says, are purposely marketing premium, consistent, high-quality distillers products. Others offer modified distillers grains — partially dried to 50% dry matter rather than 88-90%, or are adding more solubles back than normal and providing a high-phosphorus product.

“You have to know what you're dealing with,” he warns.

Dry Distillers With Solubles Can Be 30% Of Ration

At least 30% of dry matter in a dairy ration can contain dry distillers grains with solubles (DDGS) and maintain acceptable dry matter intake and milk production and composition, according to recent University of Nebraska-Lincoln research.

Thirty-four mid- to late-lactation cows were offered a control diet without DDGS or one that contained 30% dry matter in the form of DDGS. Diets were formulated to contain similar amounts of crude protein, NDF and energy. Dry matter intake as well as milk production and composition were no different for cows fed DDGS than those fed the control diet.

Wet Vs. Dry Distillers With Solubles

Wet distillers grains with solubles may have an edge over dry products as far as digestibility is concerned — but not much, says David Schingoethe, South Dakota State University (SDSU) dairy scientist.

Dry products, however, can be stored longer and shipped greater distances more economically and conveniently than wet.

Feeding wet products avoids the cost of drying them, but wet normally stays fresh only five to seven days, depending on the weather. There's also more feed loss from surface mold using wet distillers with solubles than from using dry, and added costs of preservatives if used.

Yet, Schingoethe says, some field reports show the wet product can last for up to a year. “We at SDSU successfully stored wet distillers grains with solubles for more than six months in silo bags,” he adds.