If Mike Hutjens had told dairy farmers 10 years ago that two-thirds of the forage in rations should be corn silage, some might have thought he was off his rocker. But these days many farmers are feeding that much.

"We're in corn country and have some difficulty raising alfalfa, primarily because of the lack of snow cover and subsequent winterkill," says Hutjens, University of Illinois extension dairy nutritionist. "So we're pushing our dairy rations to go past 50% corn silage to 60-65% of the total forage dry matter."

Even in Wisconsin, many dairy nutritionists are recommending a minimum of one-third alfalfa and one-third corn silage in dairy cow diets. The other third can go in either direction, depending on which is most convenient or economical.

"Many farmers can produce corn silage for less money than they can alfalfa," says Larry Satter, a dairy nutritionist with the U.S. Dairy Forage Research Center, Madison, WI.

In Illinois, Hutjens points to several factors for the growing popularity of corn silage:

- Big yields.

"It's very common for our dairy farmers here to be getting 20 to 25 tons of as-fed corn silage, which gets them in that 6 to 8 tons of dry matter/acre range," he says.

- Cost savings.

"With today's very economical prices for bean meal and other protein supplements, my data show me that the more corn silage I put in, the cheaper my feed cost/cow/day is going to be," says Hutjens. "There can be a cost savings of up to 50›/cow/day if I go to a high-corn-silage-based diet vs. a high-alfalfa-based diet."

- One-pass harvesting.

- Plant processing. Processed silage can be chopped at a 31/44" theoretical length of cut, which promotes cud chewing and proper rumen function.

- More hybrid options.

"There are high-fiber-digestibility hybrids, high-oil hybrids, soft-kernel-texture hybrids and others available to choose from. Farmers have a tremendous opportunity to pick and choose from a wide array of corn silages that fit their situations nicely vs. simply growing grain hybrids and harvesting them for silage."

While Satter and Hutjens are bullish on high-corn silage rations, both warn against overdoing it.

"I think there would be general agreement that if you get above feeding 75-80% of the total forage portion as either corn silage or alfalfa, you're pushing what should be a reasonable max," says Satter.

Adds Hutjens: "If a producer chooses to feed over 70% corn silage, he needs to work closely with a nutritionist to be sure he's got all the other ingredients right. Some low-starch byproduct feeds, such as soy hulls, beet pulp, brewer's grain and/or fuzzy cottonseed, can help ensure that he's got the correct level of carbohydrates in the feeding program."