Take a forage inventory: Ration adjustments may be required for 2019 feed quality

FREEPORT, Ill. — Compiling a forage inventory is an important task for dairymen.

“2019 was an ugly year in the Midwest with the prevent plant acres,” said Mike Hutjens, University of Illinois emeritus professor of animal sciences. “About 20 million acres were prevent plant, and a lot of that was corn acreage.”

In addition, Hutjens said during the Illinois Dairy Summit hosted by the Illinois Milk Producers Association and the U of I Extension, U.S. producers are growing a lot less hay.

“California has discovered corn silage, and they can do two crops of corn silage each year,” he said.

“If you have low quality hay below 150 RFQ (relative forage quality), sell it or feed it to dry cows or heifers,” he said. “For dairy cows, most of us want the sweet spot for hay around 170 to 180 RFQ.”

Some dairymen are seeing lower milk production than usual this winter.

“The cows aren’t milking on this year’s corn silage,” Hutjens said. “There could be some anti-nutritional factors such as mold and mycotoxins, wild yeast, dirt and ash contamination or poor fermentation.”

Hutjens recommends fermentation profiles on corn silage which measures the pH.

“You’ve got to do that because it tells you how stable the feed is and if you have risks, as well,” he said. “Spend the $25 to $30 to get it done and then you can make appropriate adjustments.”

Many dairymen harvested light weight corn in 2019.

“Typically a bushel weighs 56 pounds, but this year there are lots of guys with corn that weighed from 47 to 52 pounds,” Hutjens said. “But the good news is this corn has the same composition of nutrients, but not as much of them.”

Don’t sell the lightweight corn to an elevator, Hutjens advised.

“You’ll take a 20% to 25% hit on it and your cows will have no problem making it work,” he said. “It might be smaller kernels, so you’re going to have to really grind it fine to be sure the starch is exposed and available to be digested.”

This may be one of the problems with silage made in 2019.

“The kernels might be harder,” Hutjens said. “If I come to your farm and see any evidence of corn kernels in your corn silage, you didn’t roll it hard enough to get the job done.”

Normal corn silage typically contains about 30% starch, Hutjens reported; however, immature corn silage has approximately 20% starch.

“So, I’m missing 200 pounds of starch which means you need to feed five more bushels of corn,” Hutjens said.

Since a 1,400-pound cow will eat about 2% of its body weight, that means she consumes 28 pounds of forage dry matter every day and for a year that equals 5.1 tons of dry matter per cow per year.

“By adjusting that number for a 6% shrink and adding 30% for replacement heifers, you will need around 6.5 tons of forage dry matter per animal on your farm,” Hutjens said. “So, let’s make the decision now because you don’t want to wait until June and discover you’re out of corn silage.”

Hutjens highlighted the importance of the marginal dry matter intake or the last pound of the ration that a cow eats.

“That will give you two pounds more milk or 25 cents because the cow ate another pound of dry matter and made it into milk,” he said. “The first 13 pounds of dry matter your cow eats every day is for maintenance.”

There are several reasons a cow might stop eating, Hutjens said.

“It could be because of lameness, heat stress, overcrowding or the ration is not balanced and it has too much fat or protein,” he said. “Or, the cow is physically full.”

For forage neutral detergent fiber, Hutjens said, it should be over 50%.

“And corn silage over 60% because that effects dry matter intake,” he said. “If you have over 5.6 pounds of undigestible NDF from forages, your cows can’t eat it.”