More corn residue available for grazing

Cattle Market & Farm Reports, Editorials
Oct 15, 2007
by WLJ

Grazing corn residues is one way to reduce the cost of wintering beef cows in the upper Midwest, a North Dakota State University (NDSU) cattle expert says.

“With the increase in corn acres in North Dakota and the surrounding region this year, availability of corn residue also has increased, making this practice even more attractive,” says Greg Lardy, NDSU Extension beef cattle specialist.

Corn residue left behind after harvest includes the stalk, leaf, husk and cob, as well as downed ears. The amount of downed ears varies with the corn variety, but it can be as much as three to five bushels of corn per acre. Generally, approximately 50 pounds of residue is left on the field per bushel of corn harvested. For example, if you harvest 120 bushels of corn, you can expect about 6,000 pounds of residue per acre (120 bushels x 50 pounds of residue per bushel).

Obviously, the cow will not graze or use all of that material. At the most, a cow will be able to graze about 50 percent of that material (in this example, about 3,000 pounds per acre), Lardy says. One acre of corn residue should support a 1,000 pound cow for about 1.5 to two months. Strip-grazing the fields (dividing the field and limiting access using electric fencing) will improve utilization and allow you to increase the stocking rate.

The residue portions with the greatest nutritive value include the husk and leaf. The cob is fairly high in digestibility, but very low in protein. The stalk is low in both protein and digestibility. The longer the cattle graze a particular corn field, the lower in nutrient content their diet will be. This is due to the cattle selecting the higher-quality material first and the loss of nutrients due to weathering. Longer-term grazing may require protein supplementation to meet the nutrient needs of grazing beef cows.

Corn residue also is low in most minerals and vitamin A. Therefore, producers should follow a good-quality vitamin and mineral supplementation program when grazing corn residue, Lardy says.

Corn residue can be grazed long into the winter feeding period, provided snow cover does not limit the cow’s selectivity and grazing ability. The length of time will vary from year to year. Once fields are snow-covered, the ability of the cow to select the higher-quality portions of the corn residue is limited.

Two factors are the biggest limitations to grazing corn residue in this area of the country. First, many cornfields are not fenced and, second, many do not have adequate water for grazing livestock.

“However, the amount of residue available for grazing and its cost effectiveness should cause beef cattle producers to at least consider this option as one means of lowering the cost of winter feeding,” Lardy says.