One acre of corn stalks will provide approximately 1.5 to 2 AUMs of grazing. Cornstalks grazed shortly after harvest are higher in nutrient content than fields grazed 60 days after harvest (Rasby and Selley, 1992). Corn stalks should probably not be grazed in the spring.
Cattle will select and eat the grain first, then the husk and leaves, and finally the cobs and stalks. Cattle that have grain to select will consume a diet that is probably above 7% crude protein and as high as 70% TDN. This will exceed the protein and energy needs of a cow in mid-gestation. If corn is visible in the manure, supplementation with other than vitamins and minerals is probably not needed. However, when most of the grain has been consumed, protein supplementation is needed. A cow in mid- to late-gestation consuming only husk and leaves (no corn in manure) will need about 5 lbs. per day of average-quality alfalfa hay.
Cows should attain moderate body condition before calving (moderate condition score 5 to 6 using the scale 1 = very thin to 9 = very fat). Ohio State University Extension has a circular on how to score cows for body condition (Mangione, 1992). Dry cows will at least maintain body weight and may gain 0.5 lb. to 1.0 lb. per head daily grazing corn stalks that have grain, husk, and leaves to select. Heifers in late gestation should not be allowed to graze cornstalk fields after the grain has been consumed.
Fall-calving cows may need protein supplementation even if the cattle have grain to eat. Fall-calving cows may use unsupplemented cornstalk fields if new fields are made available at two- to Four-week intervals. Consider weaning fall calves at 90 to 120 days of age if crop residues are to be extensively utilized for the cows.
Protein supplementation is necessary for calves grazing cornstalks. There is some indication that a protein supplement with at least 0.36 lb. of escape protein per head per day is appropriate (Rasby and Selley, 1992). Total protein supplementation may need to be as high as 0.9 lb. per head per day. Average daily gain for calves grazing crop residue will be about 1 lb. per day.
Strip grazing can increase the stocking rate. Strip grazing is recommended if high levels of grain (8 to 12 bushels per acre) are left in the field. Unlimited access to excessive levels of grain can cause founder. However, if residue fields are strip grazed and it happens to snow, some of the best feed may be lost because the corn and husks are covered with snow. The lease rate for corn stalks is about $3 to $7 per acre.