Using Cornstalks
as a Feedstuff for Beef Cattle

by Grant Crawford, livestock educator, University of Minnesota Extension

As fall corn harvest and calf weaning arrive, the thoughts of many cattle producers turn to determining what sources they will use to background calves and feed cows through fall and into winter. One greatly underutilized resource for fall grazing is cornstalk residue.

This fall's Minnesota corn crop is estimated at somewhere around 1.2 billion bushels (bu.) harvested from 7.7 million acres. The residue that remains after corn harvest can be effectively used as cattle feed, with an average total digestible nutrient (TDN) concentration of 50%-55% and a crude protein (CP) concentration of 4%-6%. Although these values are low, it is important to recognize that after weaning, the nutrient requirements for cows are also very low, and can nearly be met with cornstalk grazing alone.

The most palatable parts of cornstalk residue are the husk and the leaf, so naturally these portions will be consumed first with the remaining stem and cob being less desirable to cattle. Therefore, one important consideration is the amount of husk and leaf that are available. The University of Nebraska devised a formula to determine this amount based on corn yield. The formula is:

Pounds of leaf and husk per acre = [(bu. per acre corn grain yield x 38.2) + 429] x 0.39.

This year's Minnesota corn crop is estimated to average 167 bu. per acre. Using the formula, this would result in 2,650 pounds (lb.) of leaf and husk per acre. About 50% of this will be lost due to trampling and other factors, so about 1,325 lb. will be available for grazing. This amount of residue is enough to feed a 550-lb. steer for about 85 days, and is enough to feed a 1,400-lb. cow for about 45 days.

Because the protein content of cornstalk residue is low, supplementation may be necessary. A good rule of thumb for calves grazing cornstalk residue is to supplement 0.5-0.9 lb. of protein per day. This can be accomplished with alfalfa hay at 3-5 lb. per head daily, dried distillers' grains at 2-3.5 lb. per head daily, or soyhulls at 4-7 lb. per head daily. For cows, daily supplementation of about 4 lb. of alfalfa hay, 3 lb. of dried distillers' grains, or 6 lb. of soyhulls is enough to meet nutrient requirements when grazing cornstalks.

Cornstalk residue grazing can be a low-cost, low-input method of grazing for both calves and cows. Specific attention should be paid to stocking rates and supplementation levels to ensure that this practice is completed in the most cost-effective way possible.