Managing Late-Harvested Corn Silage

As another wave of rain and now snow washes over the midsection of the country, harvesting challenges continue. For producers yet to harvest corn silage, the continuing wet conditions could lead to problems with ensiling the forage.

For every day that corn goes uncut, the crop continues to mature. “Even if the weather is wet, the plants are drying out as they mature, and you may be missing that moisture window in the plants that’s ideal for harvesting and ensiling,” says James MacDonald, a ruminant nutritionist at the University of Nebraska.

The ideal time to cut corn for silage, he says, is when plants have 35% dry matter. Starting to harvest a little early, at 32% dry matter, lets most of the crop reach that ideal moisture content of 35% during the duration of harvest window.

As plants mature past this point, reaching a dry matter content of 38% to 40%, the starch in the grain increases, boosting the energy content in the forage. But with the energy boost comes a challenge to ensiling the forage in open pits or bunkers.

The drier plant material may not ensile properly because it’s hard to pack the dry particles tightly enough to create the anaerobic environment needed for proper ensiling. Spoilage of the feed and loss of feed volume may result.

“Corn harvested at the ideal moisture content and tightly packed will lose only about 6% to 10% of feed volume during storage,” says MacDonald. “But corn that’s not ensiled properly may lose as much as 15% of dry matter material. You have less feed coming out of the pile than what went into it.”

Beware of Mycotoxins

Beyond loss of feed from lack of proper ensiling, spoilage could result. “You could get yeast and mold growing in the feed,” says Mary Drewnoski, University of Nebraska animal scientist. “For livestock, this could reduce digestibility, cause issues with the immune system, and could even lead to abortions.”

The yeast and mold may harbor mycotoxins. “You can’t see mycotoxins,” Drewnoski says. “They can be present even when silage looks good. But they’re most likely to be present when silage hasn’t ensiled properly.”

Forage analysis laboratories can test for mycotoxins.

“Dilution of the ration with other feed ingredients is the solution to dealing with mycotoxins,” Drewnoski says. “Guidelines are available to tell you how to balance the ration to counteract the level of mycotoxins in the silage.”

To promote proper ensiling of corn that’s high in dry matter, chop particles finely, spend extra time packing relatively small additions to the pack, or add water to the pile as you’re packing.

But these practices of course slow down the harvesting process. “Maybe this is the year to [bag the silage] to overcome the issues with ensiling,” he says. “It’s easier to create an anaerobic environment in an agricultural bag because the forage is easier to pack in a bag than in an open bunker.”

To safeguard your health, resist the urge to smell silage that hasn’t properly ensiled. “You could breathe in harmful mold spores,” MacDonald says.

Mary Drewnoski, University of Nebraska animal scientist

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