Use caution when using drought-stricken corn for relief feed

COLUMBIA, Mo. — Some drought-stricken corn may have more value as cattle feed than grain this year.

Droughty corn offers options when feed supplies are tight, but producers should think the process through, says University of Missouri Extension livestock specialist Gene Schmitz.

There are three main things to do before deciding to use droughty corn to feed:

• Schmitz recommends checking with your crop insurance agent before cutting. See http://muext.us/n6122 (MU Extension news release).
• Agronomist Tim Schnakenberg says producers should be aware that corn silage removes more nutrients from soil than any other crop or forage harvest practice. “This can impact nutrient levels in those fields for future years,” he says. “Be sure to keep track of nutrient levels with routine soil testing.”
• Consult with your local veterinarian and plan to test for nitrates, says MU veterinary toxicologist Tim Evans.

There are four ways to harvest a failed corn crop: green chop, grazing, silage and baling. Each comes with risk, says Schmitz.

Schmitz and other MU Extension specialists recently gave tips on what to do with droughty corn:

Watch moisture levels. If you decide to bale corn for dry hay, ideal moisture is between 14% and 18%. If too wet, the hay will heat, then mold and, in extreme cases, catch on fire, says MU Extension state forage specialist Craig Roberts. Mowing with a crimper will break the stems and let the forage dry faster.

Rolling up corn and ensiling the bale is possible, but it is not a common practice. If you decide to bale corn for baleage, it will need to be wet enough to allow for a tight bale.

A dry bale, with moisture level of 40%, will not pack tightly and will end up with too much oxygen. That leads to moldy feed that will go to waste and affect animal health, says Roberts. Based on work with other coarse grasses, Roberts suggests a moisture level of 55%.

It is hard to make a good, tight bale with corn, he says. Use the baler’s highest tension setting and wrap tightly with a layer of netting first and then plastic.

Also, balers likely will roll up dirt with the stalks, and there will be long, unbroken stalks, which will make the feed less desirable to cattle.

For more information, Roberts recommends an article from Oklahoma Farm Report, “Hay Harvesting Tips for Failed Corn Crops,” at http://oklahomafarmreport.com/wire/news/2011/07/01608_HayHarvestingCorn_105406.php.

Ideal moisture for chopped silage is 65%. Silage that is too wet can spoil; silage that is too dry is difficult to pack, says Schmitz. Cover silage with plastic as soon as possible and inspect silage bags for holes that need repair. The key is to keep oxygen out, he says.

Nitrates dissipate some from silage during fermentation, but they need time to do so, says Schmitz. Feed only after silage has fermented three weeks or more to reduce nitrate levels in silage. Test silage for quantitative nitrate concentrations and nutrient content after fermentation is complete.

For more information, see the MU Integrated Pest Management article “Making Silage From Drought-Damaged Corn” at https://mizzou.us/IPM2012a.

Test nitrate levels. Veterinary toxicologist Tim Evans recommends consulting with your local veterinarian and local extension specialist before cutting. Nitrate in forages becomes nitrite in the rumen. Nitrite changes hemoglobin so it does not bind oxygen in an animal’s blood, causing suffocation and possibly other adverse health effects. Nitrate amounts do not decrease when corn is baled as hay.

The highest levels of nitrates are in the bottom 10 inches or so of stalk, Evans explains. Agronomists have suggested leaving taller stalks as residue to reduce nitrate risk, lessen erosion and maintain moisture in during winter.

In a press release, Evans said “In years without drought concerns, we often aim to keep nitrate concentrations at a ‘safe’ dietary level of less than 0.25% (2,500 ppm), especially for cows in late pregnancy. However, current drought conditions will likely make it very difficult for producers to maintain this ‘safe’ dietary nitrate concentration and may force them to feed their pregnant cows  – even those in the third trimester  – dietary nitrate concentrations in the ‘caution’ range between 0.25% and 0.5% (5,000 ppm). Likewise, producers may also have no other choice than to feed their other cattle dietary nitrate concentrations at the upper end of that range to potentially higher dietary concentrations of nitrate.”

“Reducing the risks associated with feeding forages at and above the ‘caution’ range will require producer consultation with extension personnel and their veterinarian, supplementation with grain, gradual introduction of fed cattle to new forages and supervision of cattle eating any alternative feeds,” he adds.

Learn more about nitrate/nitrite intoxication in cattle in these MU Extension publications available for free download:

“Nitrate Problems in Livestock Feed and Water,” https://extension.missouri.edu/g9800

“Drought-Related Issues in Forage, Silage and Baleage,” https://extension.missouri.edu/agw1017

Mix high-nitrate forages with lower-nitrate forages and other feed to dilute nitrates for feeding. If feeding baled stalks, do a hay test on the inner core of the bale.

Use extra caution with green chop. If you decide to green chop corn for feed, cut and feed as you go. Green chop from drought-stressed corn should be cut and fed 2-3 times daily.

Do not leave green chop in piles or a wagon overnight as this greatly increases the risk of nitrates turning to nitrites, which are the actual poison that harms cattle. If possible, test quantitative nitrate concentrations and possibly nutritional quality before feeding and increase daily feeding amounts gradually.

Extension personnel can perform qualitative spot testing for nitrate using diphenylamine to demonstrate whether any nitrate is accumulating in forages or how high the nitrate is accumulating in cornstalks.

“Although it would be surprising under current drought conditions to not detect nitrate in forages with this test, producers may need to know immediately if nitrate is accumulating in forages, and this test can be used to indicate if quantitative nitrate testing is needed,” says Evans.

Weeds in pastures or fields that are green chopped also can cause issues, says Evans. Common weeds such as pigweed, ragweed, lambsquarters, nightshade and Johnson grass can elevate nitrate levels in feed. As a rule, cattle will graze around most of these weeds in pastures, but they will eat them in green chop.

Evans also warns that corn that was cut, greened up after a rain for 5-7 days and cut again should also be monitored for high nitrate concentrations.

Supplement heavily. Limit access to high-nitrate feeds and supplement heavily with grain or other mixes, says Eric Bailey, extension state beef nutritionist. Adding supplements dilutes nitrates as they pass through the rumen. See the MU Extension publication “Drought-Related Issues in Forage, Silage and Baleage” at https://extension.missouri.edu/agw1017 for more information on using high-nitrate feeds.

Consider herbicide carryover. Weed scientist Kevin Bradley says drought increases concerns of herbicide carryover and persistence in crops like corn grazed or hayed as relief crops.

Without rainfall to increase metabolism, herbicides may remain longer in plants and the soil.

Label instructions may restrict feeding some crops as livestock feed, Bradley says. Cows may be able to metabolize the chemicals, but residue levels could pass through the milk or remain in the meat.

Bradley recommends always following label restrictions pertaining to feeding or haying.

Grazing is risky and requires monitoring. Restricting cows’ access to cornfields requires temporary fencing, but other harvest costs are eliminated.

Do not turn hungry cows into a cornfield with unlimited access, says Schmitz, and only after feeding them good hay so that they don’t overeat. Strip graze, increasing access to corn gradually. Do not force cows to eat the lower portion of the stalk, which contains the most nitrate.

Consider costs. “There is no inexpensive way around this roughage shortage,” says Bailey. Silage can be expensive to transport long distances. Improperly harvested silage and baleage can go to waste, which increases expense and uses time and labor without producing additional feed.

This is part of an MU Extension series to help row crop and livestock producers manage drought.

More information: “Corn Silage,” https://extension.missouri.edu/g4590.

For more drought resources, go to https://mizzou.us/DroughtResources.