Managing late-harvested corn silage

Take precautions when harvesting maturing corn to ensure proper ensiling.

As another wave of rain and snow washed over the midsection of the country last fall, harvesting challenges continued. For producers who still had to harvest corn silage, the ongoing wet conditions could lead to problems with ensiling forage.

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 the 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. With the energy boost comes a challenge in 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,” MacDonald says. “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.”

Watch for spoilage

Beyond loss of feed from lack of proper ensiling, spoilage could also 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 even lead to abortions.”

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

Forage analysis laboratories can test for mycotoxins. Drewnoski says the solution to dealing with mycotoxins is dilution of the ration with other feed ingredients. 

“Guidelines are available to tell you how to balance the ration to counteract the level of mycotoxins in the silage,” she says.

Practices for proper ensiling

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.

These practices, of course, slow down harvest. 

“Maybe this is the year to bag the silage to overcome the issues with ensiling,” Drewnoski 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.

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