Pork producers should test the new corn crop before feeding it, according to a Purdue University Extension swine specialist.

That’s because mold is present in corn in much of the Midwest, says Brian Richert. In fact, a couple producers who started feeding new crop corn had near 100% feed refusal because of the high vomitoxin levels in the corn.

“Those producers had to suck all that feed back out of the feeders, find a source of new feed and try to get feed back in for those animals,” he says. “It can cause some significant problems if producers don’t test their corn up front.”

Pigs will have reduced feed intake when deoxynivalenol (DON) levels are above 2 parts per million (ppm), and near complete feed refusal when DON levels are at 10 ppm or greater in the complete diet, Richert says.

There are a couple of options for producers to consider.

“If the corn is not harvested yet and you are not going to get to it for a week or two because of soybean harvest, you can walk the field and take a representative sample, shell it and send it in to a diagnostic lab or to a grain company for a mycotoxin analysis,” he says. “If you are harvesting corn, but can buy a little time by feeding old crop corn or purchasing feed for livestock, that will give you time to get your corn in a bin and test it.”

Once the corn is stored in the bin, there could be a dilution effect and producers should take multiple core samples to blend and submit for analysis.

“Once you know what you have, then you can manage it,” Richert says.

When the test results are back, producers should ask:

What are we going to feed as a dilution? How much can we feed? Do we have a source of clean corn to blend down to an acceptable level that still provides adequate performance in livestock? Do we have to source other feed ingredients to help with the blend down and cut the amount of high vomitoxin or zearalenone levels in corn?

Producers who have breeding stock on their farm should have corn tested specifically for zearalenone, a toxin that is produced by the mold Giberella.

“If levels are too high, above 3-5 ppm, it could impact the breeding herd,” Richert says. “Replacement gilts may not cycle and there could be problems getting sows bred.”

Diplodia, another mold found to be common in this year’s corn crop, can produce low test weights and is prone to shattering, which creates a lot of fine material, Richert explains. Diplodia doesn’t produce a toxin and is safe to feed, but could inhibit feed intake due to the moldiness of the corn, he says. Long-term shattering and fine material are concerns during storage, because they increase the susceptibility to other molds including those that produce aflatoxin or ochratoxin.

Producers can change the palatability and hide the taste with flavoring agents for Diplodia-infected corn, he says.