UNL Extension Specialist discusses considerations for grazing corn residue
Providing cattle with quality forage through winter months is one of the largest costs on an operation. Therefore, producers looking for ways to decrease feed costs during the winter might consider utilizing corn stalks. In fact, the combination of dropped ears, grain, husks and leaves provides an adequate, cost-effective ration for cattle.
“Having corn stalks to graze is a great resource for livestock producers,” says University of Nebraska-Lincoln Extension Educator Brad Schick in a UNL BeefWatch newsletter published Oct. 1. “Grazing not only provides a relatively inexpensive feed, typically meeting cattle’s nutritional needs, it can also help get rid of corn remaining in a field and potentially reduce volunteer corn the following year.”
During a corresponding BeefWatch podcast, Schick notes the first consideration when grazing corn residue is to analyze the quantity and quality of feed left in the field.
“In everyday conversation, grazing corn stalks is said, but the stalk is the last thing cattle eat,” says Schick. “Cattle do eat stalks, particularly if they are left on the field too long, but they are primarily consuming leaf, husk and leftover corn.”
Schick goes on to note the stalk makes up about 48.5 percent of residue, while the leaf and husk make up 39.6 percent.
“Cattle will consume the leaf and husk if they are available. This consists of 52 to 55 percent total digestible nutrients (TDN) and five to 5.5 percent crude protein,” Schick says.
He explains corn left on the ground is the highest-quality material left in the field following harvest, so cattle tend to graze it first.
With this in mind, Schick explains the quality of the field being grazed will decline over time – partially due to cattle grazing the higher-quality material first and partially due to weather.
In addition to the quality of residue cattle will be grazing, Schick notes it is also important to consider the quantity of residue left in the field. He points out it is especially important to analyze the amount of corn left in the field in order to minimize the risk of grain overload.
According to Schick, producers can do this by performing an ear count. This can be done by walking three 100-feet strips in the field and counting the number of ears on the ground. The number of bushels on the ground per acre is equal to this number divided by two.
“Any given year, there will be about one to five bushels on the ground per acre. However, the threshold is 10 bushels per acre, which is equal to 560 pounds per acre. If producers get up in this range, they are going to want to manage the amount of access their cattle have,” Schick explains.
He also notes if producers have fields close to this threshold, they should gradually allow cattle access to the field.
“Cattle shouldn’t go straight from grass to 10 bushels of corn per acre,” he says. “We want to work them up to it.”
In order to restrict access, Schick says producers can utilize strip grazing, limit the amount of time cattle are in the field or only allow access to certain portions of the pasture.
Length of grazing
When thinking about how long to graze residue, Schick says the calculation to follow is that for every bushel of corn produced, there is 16 pounds of dry leaf and husk.
“The recommended grazing plan should be to remove 50 percent of the leaf and husk,” Schick explains. “This assumes the other portion of the forage will be lost to trampling, defecation and wind.”
With this in mind, Schick notes the calculation is eight pounds of good forage on a dry matter basis available for consumption for every bushel of corn.
“Say the field produced 200 bushels of corn per acre. By the calculations, there is 1,600 pounds of dry matter per acre available,” he explains. “A 1,000 pound animal will consume about 26 pounds of dried forage per day, which means a 1,300 pound animal will consume about 34 pounds per day.”
“However, with lower-quality forage such as corn residue, intake will be closer to two percent of bodyweight. In this example, it is closer to 26 pounds for the 1,300 pound animal,” he continues. “By the calculations, there are 61 days of grazing for one cow grazing one acre. A general rule is about 30 cow days per 100 bushels of corn produced.”
Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.