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, says a Purdue Extension forage specialist.
Damaged corn can be harvested as either whole-plant silage or green chop, but, either way, growers and livestock producers need to be aware of how it can affect feed quality and animal health.
“Feeding value of drought-stressed corn is influenced by several factors but in general is higher than expected,” Keith Johnson said. “Most studies indicate feed value of drought-stressed corn to be 80-100 percent 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 said drought-stressed corn will have slightly more fiber and less energy, but 1-2 percent 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 said. “For upright silos, to avoid seepage, growers should harvest at 60-65 percent, whereas for bunker silos, harvesting at 65-70 percent moisture will result in better packing and storage qualities.”
He said producers often 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 said. “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. While the potential for nitrate toxicity after fermentation is reduced, Johnson said it’s still a good idea to have the feed analyzed.
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.”