The stocking rate of crop residues is a function of grain yield. The greater the yield, the more husk and leaves, and thus more that is available for the cow to consume. Due to new genetics for corn, stalks are more disease-resistant and stronger, and there is less ear-drop for cows. The following is a way for you to calculate the information you need. For a corn field that yields 150 bu of corn per acre, an acre of stalks should carry a cow for about 45 days. Residue (leaf and husk) yield is related to grain yield, but hybrids obviously vary in this relationship. With high-producing corn (irrigated or with ample rainfall), there will be about 16 lb dry leaves and husks per bushel of corn yield. Some residue disappears through trampling and other factors. We usually estimate 50% utilization of the leaf and husk by the grazing animal. Therefore, 150 bu of corn produces 2,400 lb leaves and husks per acre on a dry matter basis and 1,200 lb (50% of the total 2,400 lb) of husks and leaves on a dry matter basis available for the animal to consume. Forage intake is a function of forage quality. As forage quality increases, forage intake will increase. Corn stalk residue would be considered an average quality forage. Cows consuming this forage should be able to consume 2.2% of their body weight on a dry matter basis. Therefore, a 1200 lb cow will eat about 26.4 lb of the residue on a dry matter basis daily. If there is 1,200 lb of residue on a dry matter basis available, then an acre of corn stalks will provide about 45 days (1,200 lb of residue/26.4 lb daily intake) of grazing.

Using the same concept an acre of this corn residue should allow a 600-lb calf about 90 days of grazing. Higher grain yields provide more grazing days and lower yields less.

Snow cover and ice will reduce grazing days and the manager needs to monitor the cattle in these situations to make adjustments.