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Can I graze wildfire-damaged cornstalks?

Zoran Kompar/Getty images Burned corn field
TO A CRISP: Fall’s harvest season was one for the books, with excessive high wind, little precipitation and low humidity, causing the perfect storm, not for rain, but for combine and field fires.
Fire-damaged cornstalks are safe to graze, but lower energy contents will require a protein supplement and extra roughage.

With high winds, low humidity and severe drought in Nebraska and the Plains states, it was a perfect storm for fires in 2022. Following a spring and summer that was packed with wildfires, both large and small, harvest season was particularly hazardous, especially on days with high winds. Many producers who experienced these fires on unharvested or harvested cornfields wonder if they can safely turn cattle out to graze fire-damaged grain this winter.

“Fire-damaged grain, if not completely destroyed, will have an appearance ranging from a slight brownish tint to black,” states Mary Drewnoski, Nebraska Extension beef systems specialist, in a recent University of Nebraska CropWatch article. “This grain can be salvaged and fed to cattle.”

Check by color

The common methods used by commercial laboratories to evaluate the energy content of damaged corn will not provide an accurate estimate of energy-availability for heat-damaged corn, according to Drewnoski.

“However, color can be used as a crude indicator of the relative energy available for cattle,” she says. “Based on research conducted by Iowa State University, the amount of starch from brown to black corn that was digested in the rumen was about 30% less than normal corn,” she says. “This corn would still have a significant amount of energy and can be used as an energy source.”

According to ISU, mild exposure to heat may slightly tint the outer seed coat from yellow to tan, but longer exposure and higher temperatures will turn the seed coat black. If the inner starch of the kernel is still white to tan in color, the feeding value may still be relatively good, says the ISU study.

But if you are grazing fire-damaged fields, cattle need to be adapted to corn, or have limited access to avoid acidosis. “Strip grazing is one method,” Drewnoski says. “Due to the fire removing the residue in the field, cattle will need to have a roughage source, such as hay, provided when grazing.”

Drewnoski suggests that grazing weaned calves on heat-damaged cornfields could be an optimal way to utilize the feed. “It is recommended to have them used to consuming at leave 5 pounds of corn before turnout,” she says. “In addition to a roughage source, these calves will need supplemental protein to make best use of the energy in the corn. Alfalfa hay could be used as a source of protein and roughage.”

Free-choice grass hay plus 2 pounds of dried distillers grain is another option.

Cull cows

The next best option for utilization would be using the corn to put on extra weight and increase value of cull cows. They should be fed grain ahead of turnout, working up to 7 to 10 pounds over a week to 10 days, Drewnoski says. Otherwise, strip grazing can be used to adapt the cows to the corn.

To learn more, contact Drewnoski at [email protected], or visit UNL CropWatch.






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