With U.S. farmers expected to harvest about 12 billion bushels of corn this fall, there will be ample opportunities for incorporating corn stubble into growing and backgrounding programs. Grant Crawford, a regional educator with the University of Minnesota Extension, says that in spite of the value of corn residue as a low-cost feed for weaned calves, only about 25 percent of crop residues nationwide are actually used.

Based on last year’s average corn yield of 146 bushels per acre in Minnesota, Crawford says each harvested acre will contain approximately 3 tons of crop residue dry matter. With improvements in harvesting machinery, farmers have reduced residual grain loss to less than 1 percent of total grain yield, meaning that less than 80 pounds of residual grain remains on that 146-bushel acre. Husks and leaves, though, have high palatability and offer about 3.6 and 7.8 percent crude protein, respectively. Stems and cobs, at 4.5 and 2.2 percent crude protein, are less palatable, and cattle typically consume them only after most other residue is gone from the field.

Because of this selective grazing, the overall digestibility of available forage declines over the time calves graze a stubble field. Crawford notes that in a University of Nebraska study in which 90 steers were grazed on 90 acres for 95 days, residue digestibility decreased from 56 percent at the beginning of the corn stalk residue grazing period to 47 percent at the end of the period, for an average of 55 percent. He suggests using some form of strip grazing to periodically allow calves access to ungrazed, highly digestible residue.

Optimizing stocking rate is critical for efficient forage utilization and good weight gains. To determine the best stocking rate, first estimate the amount of forage available. Crawford suggests a formula developed at the University of Nebraska that estimates available leaf and husk weight per acre based on corn yields.

The formula is: pounds of leaf and husk per acre = ([bushels per acre corn yield x 38.2] + 429) x 0.39.

For that 146-bushel-per-acre field, this would result in approximately 2,300 pounds of leaf and husk per acre. Assuming that about half of the forage will not be available due to trampling or other loss, approximately 1,150 pounds of leaf and husk residue per acre will be available for consumption. So, Crawford says, 1 acre of residue at that yield level could support a 550-pound steer consuming 14 pounds of dry matter per day for 82 days.

Some form of supplementation is necessary to account for the low levels of crude protein in corn residue. Crawford says a good rule of thumb is to provide 0.5 to 0.9 pounds of supplemental protein per head per day.

Alfalfa hay fed at 3 to 5 pounds per calf per day can fit the bill but might not be cost effective, depending on local hay prices. Byproduct feeds such as dried distillers’ grains and corn gluten feed are excellent sources of protein that can work well in stubble-grazing programs. DDG contains approximately 28 percent crude protein and will provide adequate protein at a rate of 2 to 3.5 pounds per calf per day. Corn gluten feed, at about 20 percent crude protein, should be supplemented at approximately 2.5 to 4.5 pounds per calf daily, Crawford says. Soyhulls are another option, supplemented at 4 to 7 pounds per calf per day.

In most situations and at typical stocking rates, Crawford says 550-pound steers on corn residue will gain about 1.1 pounds per day without additional supplementation besides protein, vitamins and minerals. If a producer’s marketing goals require faster gains, some form of energy supplementation likely will be necessary.

For more information from the University of Minnesota’s Beef Extension program, click here.