Severe drought conditions across much of the country has producers looking for alternative uses for their crop. A Purdue Extension forage specialist says farmers with drought-damaged cornfields could consider harvesting the crop for livestock feed to salvage some of its value and to help livestock producers supplement short forage supplies.
Damaged corn can be harvested as either whole-plant silage or green chop. Keith Johnson noteds, "Most studies indicate feed value of drought-stressed corn to be 80% to 100% that of normal silage." Purdue University studies showed little or no difference in feedlot gain or milk production when beef and dairy cattle were fed normal or stressed corn silage. But, as a rule, Johnson says drought-stressed corn will have slightly more fiber and less energy, but 1% to 2% more protein than normal silage.
One of the most influential factors is moisture content at harvest. "Ideally, the crop should contain 60% 70% percent moisture at harvest," Johnson says. He elaborates that for upright silos growers should harvest at 60% to 65% (to avoid seepage) while those with bunker silos should harvest at 65% 70% moisture for better packing and storage qualities.
He also notes producers tend to harvest the damaged crop too soon, meaning silage has too much moisture, which can result in poor fermentation and ultimately lower feed value. Stalks of plants with brown leaves and stalks with small ears or little grain content will be higher in moisture.
"A quick way to determine if the plant contains too much moisture is to hand-squeeze a representative sample collected from the forage chopper," Johnson says. "If water drips from the squeezed sample, the corn is too wet for ideal fermentation."
Livestock producers using drought-damaged corn for silage need to make sure they have the feed tested for nitrate. Nitrate levels can be higher in drought-damaged corn.
Producers with short pasture and stored feed supplies might also consider harvesting drought-damaged corn as green chop. "There are two major concerns with this practice," Johnson said. "One is the potential for nitrate toxicity and the second is the potential to founder animals." To avoid such problems, he offered this series of steps:
- Raise the cutter bar to 12 inches the first few days of chopping.
- Gradually introduce animals to green chop.
- Use other feeds that are low in nitrate as part of the ration.
- Feed green chop in small quantities throughout the day, rather than large quantities once per day.
- Don't allow green-chop forage to set on a wagon overnight.
- Feed 2-3 pounds of grain with high nitrate feeds.
- Take extra precautions during the first 2-3 days following rain because nitrate levels tend to increase during this period.
"As plants mature, nitrate levels decline, so animals become acclimated and the chances for toxicity decrease over time," Johnson elaborates.
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