A lot of acres of corn have been harvested in Ohio this fall. For every bushel of corn harvested by the combine, between 14 to 16 pounds of corn residue dry matter is left in the field.
"Graziers need to view that residue as a resource opportunity," says Rory Lewandoski, OSU Extension specialist. "That remaining corn residue is composed of corn grain, cob, husks, leaves, and stalks, all of it with some nutritional value."
Corn residue, when grazed during a mid-October through December time frame is a suitable feedstuff for most classes of ruminant livestock Lewandoski says. The exceptions are livestock in a late gestation or lactation stage of production. In addition to using a low cost feedstuff, grazing corn residue removes animals from grass pastures during the late fall period. This can benefit pastures, insuring that they are not overgrazed before they go dormant. Grazing corn residues can help to stretch stockpiled forages so that they are not used until later in the year.
The nutritional value of corn residue varies depending upon how the residue is grazed, the amount of time that has passed between harvest and grazing and environmental conditions. According to a South Dakota State University Extension publication entitled "Grazing Corn Stalks" a crude protein content of 8% and a total digestible nutrient content of 70% can be expected early in the grazing period. Over time the nutritional content will decrease to 5% CP and 40% TDN.
"This is a typical pattern where livestock are provided with an entire field or a large section of a field and allowed to graze over an extended time period of 30 to 60 days," he says. "The nutrient content decreases because livestock are selecting the highest quality, most palatable portions of the residue first and because nutrient content decreases as the residue weathers and soluble nutrients are leached out."
A University of Nebraska study conducted over a 5-year period from 2004 to 2009 measured corn grain left in the field after harvest. An average of 1.0 bu/acre was available for livestock grazing. A 2004 Nebraska beef report on corn stalk grazing included more information about the make-up of corn residue. Generally, stalks account for 49% of the residue dry matter, leaves 27%, husks 12% and cobs another 12% of the residue dry matter. Livestock typically consume any corn grain first. After the grain, plant leaves and husks are eaten and the last portions of residue eaten are cobs and stalks. Strip grazing across a field can even out the nutritional quality because livestock will be forced to consume both the higher and lower quality components of the residue within a given grazing period before the fence is moved to provide a new strip. A 2004 Nebraska beef report on corn stalk grazing listed the average TDN value at 54-55%.