– Jeff McCutcheon and Dave Samples, OSU Extension Agents
Ohio produces over 3 million acres of corn each year. Most of those acres are harvested for grain with the rest of the plant left in the field. In addition to the value of the grain, one acre of corn residue can supply enough forage to sustain a 1,000-pound cow or animal equivalent for 1.5 to 2 months. Any quick calculation you do, should lead to the conclusion that there is enough feed remaining on corn fields after harvest to significantly increase the grazing days for ruminant livestock. The use of corn residue offers producers increased flexibility for fall and winter pasture and helps reduce the overall feed costs.
Ideally corn fields should be used immediately after harvest for 30-60 days to take maximum advantage of the feed value of the residue. This would allow the permanent pastures to “stockpile” additional days of fall growth that could be grazed after the animals come off the corn fields. Grazing corn fields for an extended period, even all winter, is also an option if supplemental feed is provided and the fields remain dry.
Livestock will selectively graze the most palatable portions of the residue first, starting with the grain, leaves, and husks and then the cobs and stalks. Generally, animal grazing will leave 75-80% of total residue in the field, especially if animals are rotated to new areas before much of the cob and stalk material is consumed. With this in mind, one acre of corn residue will yield approximately 60 animal unit grazing days. This means that one acre of corn residue will provide 60 days of grazing for a 1,000-pound animal, or 30 days for two animals.
Limiting access by strip grazing will allow for an increased stocking rate and greater utilization of the residue. This can be accomplished by using portable electric fencing. Either a single break wire to the front, or double wires with one in front and one to follow can be used effectively, depending on the layout of the field and water sources. However, if strip grazing practices are used, and snow cover arrives before the field is grazed through, some of the best feed may be lost if the grain and husks cannot be recovered.
The easiest fit for grazing crop residue is with non-lactating, mature beef cows or ewes that are in the middle trimester of gestation and are in desirable body condition. Animals that have grain to select will consume a diet that is probably above 7% crude protein and as high as 70% Total Digestible Nutrients (TDN). If corn is visible in the manure, supplementation with anything other than vitamins and minerals is probably not needed. However, when most of the grain has been consumed, or little grain is left in the field, protein supplementation will probably be needed. Several studies have shown that dry cows will at least maintain body weight and may gain up to 1.0 pound per head daily while grazing corn stalks that have grain, husk, and leaves to select.
For other classes of livestock like first calf heifers, ewe lambs, fall calving beef cows, lambs, and calves, supplementation will be needed. These classes of animals have higher nutritional needs than average corn residue can provide and producers cannot afford to ignore those needs.
For more information check out the OSU Extension fact sheet on grazing corn stalks at: http://ohioline.osu.edu/anr-fact/0010.html or call your local Extension Office.