LINCOLN, Neb. -- Dry conditions this summer have many producers turning to alternative methods of salvaging what's left of heat damaged corn, a feed source that can be dangerously high in nitrates, a University of Nebraska-Lincoln forage specialist said.

Producers need to take special precautions when feeding corn forage and other annual grasses to livestock because of high nitrate levels. However, it is possible to safely feed livestock from such feed sources if producers are aware of proper harvesting and feeding techniques, said Bruce Anderson, forage specialist in the university's Institute of Agriculture and Natural Resources.

"Nitrates in corn forage should be respected instead of feared," Anderson said. "Considering the available testing and feeding options, most producers can safely feed corn if they are aware of how serious the problem is."

When conditions are extremely hot and dry, the metabolism of the corn plant slows down, and the plant isn't able to convert the nitrates absorbed from the soil into beneficial nitrogen compounds such as proteins, Anderson said.

There is a number of options available for producers that reduce the risk of nitrate poisoning, Anderson said.

Nitrates are most abundant in the lower six to eight inches of plant stems. Unless this portion of the plant is grazed or harvested, toxic nitrate levels should not be a threat to livestock.

"Most grazing animals won't eat the lower portion of plants, unless they are forced to graze an area short," Anderson said. "The best poison prevention is to control type and quantity of forage offered to livestock. Don't turn animals out when they are very hungry, and don't allow them to eat the bottom six inches of summer annuals."

In addition to grazing, drought-stressed corn can be harvested for silage or hay. Both of these methods result in a fairly safe product as long as proper precautions are taken, Anderson said.

The fermentation process can reduce up to half the nitrates in corn cut for silage, Anderson said. However, in order for this to occur, moisture levels must be reduced to 65 percent to 70 percent before ensiling. This is best done by letting corn naturally mature and dry to the proper moisture before chopping. Producers also can cut corn and let it dry in the field or mix silage with dry ingredients to take in some of the moisture.

Hay should be cut 8 to 12 inches above the ground to avoid the high nitrate levels found in the bottom portion of stems. It also must be allowed to reach appropriate moisture levels before baling, otherwise heavy mold growth could occur, Anderson said.

Green-chopping is a riskier option for producers. Green chop should be fed immediately after chopping and not allowed to heat in the truck or bunk. Heat causes nitrates to convert to nitrites, which are 10 times as toxic when fed to animals. The best method is to only chop what can be eaten within two hours, Anderson said.

"Always test nitrate levels in the green chop, hay or silage before feeding it to animals," Anderson said. "If nitrate is higher than the potentially toxic level, use this feed for only a portion of the total ration, with the balance of the ration comprised of lower nitrate sources."

Legume hay such as alfalfa, prairie hay and other perennial grasses and grains all help reduce nitrate levels, Anderson said. Grains are especially effective because they help microbes in the rumen incorporate nitrates into a safer product.

"Regardless of what you do to reduce nitrate levels in your feed, never assume your feed is safe. Always collect samples, especially from what might be the most hazardous feed, and analyze them for nitrates before feeding. Then use these test results to guide you toward safe feeding," Anderson said.

Samples can be taken to commercial laboratories for feed analysis, Anderson said.

Nitrate poisoning can be fatal and includes symptoms such as labored breathing, excessive salivation, bloating, tremors and immobility, Anderson said. If nitrate poisoning is suspected, a veterinarian should be contacted immediately. Cattle should be handled as little and as quietly as possible until the veterinarian arrives to administer a treatment to counteract the nitrate.

"In any drought year, nitrates pose a high risk," Anderson said. "Producers just need to use diligence and consistency in the feeding process."

For more information about drought-stressed corn, consult UNL Extension NebFact NF02-547, Drought-stressed Corn, available online or at local extension offices.

SOURCE: IANR news release from University of Nebraska-Lincoln.