Dr. Darin Bremmer: Practical Application & Economics of High Corn Silage Diets

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By Judy Brown, contributing writer
A double whammy of widespread alfalfa winterkill and drought the past few years is driving more dairy producers to adopt high corn silage diets.

Producers tired of trying to obtain high quality hay and haylage are shifting to high corn silage diets said Dr. Darin Bremmer, Vita Plus dairy nutritionist and technical services advisor, serving Wisconsin producers in central Wisconsin.

When obtaining his doctorate from the University of Wisconsin-Madison, Bremmer's research centered on ketosis, fatty liver and transitional cows.  While the risk of mycotoxins may follow several years of corn, corn, and more corn, he said the benefits of moving to a high corn silage diet are numerous.

"There are a lot of things to think about when moving to a high corn silage diet," he said. "We need consistency. Cows need consistency."

In addition, for the corn silage strategy to work, producers need a four-month carryover.  That’s because corn silage digestibility increases after three to four months in the bunker, he noted.

"It costs extra money to inventory three to four months of extra corn silage," he said. "But it also costs money not to inventory three to four months of extra corn silage.  It's always important to process corn silage well and longer material contributes effective fiber," he said.

It used to be that a cow diet high in corn silage had about 50 percent of the forage, but now he considers 93-percent corn silage as the high standard.  Cows require a well-balanced diet, but that doesn't necessarily require haylage, he said.

Compared to alfalfa, he said corn silage is more consistent and more uniform.  However, nutritionists must acknowledge that, to work corn silage into a TMR, they must account for a wide variability of starch in corn, he said, noting he found it ranged from 8 to 37 percent starch this year.

"We have to monitor NDF and total NDF because it's one of the driving factors in consistency," Bremmer said.

However, he's also seen inconsistency when measuring dry matter in haylage bunkers ranging from 38 percent to 51 percent.

"We can end up with a lot more inconsistency in haylage bunkers," he said.

Emphasizing consistency, he said that cows "like consistent diets and a cow's rumen doesn't like change."  Very few changes need to be made over a week with a well-balanced corn diet whereas changes are sometimes more dramatic in the content of haylage in a bunker.

"A lot of people still have the mindset that haylage is more economical because of the value of protein," he said.  "It just costs more to harvest alfalfa.”

Bremmer cited studies for producers looking to validate cost savings if they switch all in to corn silage over haylage.  Cost studies were based on Wisconsin's average of 8 tons of dry matter per acre in corn silage and 5 tons of haylage covering five cuttings.  The study showed a $640-per-acre cost to raise and harvest corn silage or $28 per ton when fed.  That compares to $600 per acre for alfalfa or $54 per ton as fed.  Corn silage harvest costs were put at $115 per acre, while alfalfa harvest costs were pegged at $71 per acre times four.

Measuring the impact of corn silage on total feed costs, based on corn silage at $50 a ton and alfalfa at $150 a ton, found differences when the ration contained either 50 percent or 93 percent corn silage.  The advantage went to the 93-percent program at $6.88 per cow per day compared to $7.90 per cow on the 50-percent regimen.  Bremmer said that using actual costs to produce haylage improves the value of protein in haylage when compared to other commodities.

"The difference tightens, but the advantage is still corn silage," he said.

When comparing corn silage with alfalfa, he grants that alfalfa provides ground cover that corn cannot.  However, he said corn can be followed by rye, triticale or wheat. He advised producers to be aware of the qualifications relating to crop insurance and harvest times for these cover crops.

Bremmer shared these additional points with Dairy Summit attendees:

• Milk protein is typically higher in higher corn silage diets.
• Highly digestible starch can make it a challenge to hold butterfat, especially in summer.
• Cow manure will tell the most about the effectiveness of fiber in the diet. The goal should be less than 3 percent of corn starch in manure.
• Don't give up kernel processing to get more length. Making longer corn silage that ends up in refusals adds no effective fiber.