Corn residues left on the ground after grain harvest may be utilized as a significant source of fall and/or winter grazing for beef cattle. It is estimated that half of a corn plant's dry matter production is in the form of grain; the other half is left on the field as unharvested grain, husks, leaves, cobs, and stalks. This half of the plant's production is potentially available as a roughage, energy, and low protein feed source for grazing ruminants. With low cost electric temporary fencing, cornstalk fields may significantly decrease winter feed costs and possibly reduce permanent pasture requirements per cow. Grazing of corn residues has been described in a number of beef production systems including weaned calf backgrounding, although grazing of weaned, late bred cow is most common.
The potential for grazing on corn residues offers increased flexibility for fall and winter pasture. Cornstalk grazing may be matched with permanent pasture grazing in the fall to optimize total feed available. For example, corn fields may be used for 30 - 60 days fairly intensively while grass pastures "accumulate" fall growth. Total grass available for late fall will increase and permanent pasture grazing may be extended further into the winter, perhaps reducing winter feeding by 30 days or more. Grazing cornstalks for extended periods of time, even all winter, with additional supplementation is also and option, especially when permanent pastures like coastal bermudagrass do not offer much fall growth.
An acre of stalks from a 100 bushel per acre field should yield about an equal weight of residues, or about 5600 lbs. Cattle tend to only consume about one fourth of that, so 1400 lbs. are possibly consumed. 22 The NRC requirements of a 1200 lb. non-lactating and late gestation cow are about 19.4 Mcal of metabolizable energy and about 1.7 lbs. of crude protein, under normal conditions. These needs can be met by consumption of about 24 lbs. of corn residues and cows tend to eat at least this much and gain one fourth to one lb. daily if given free access to cornstalk grazing. With 1400 lbs. available for consumption, one acre may provide enough nutrition for 2 cows for about 30 days, or one acre may be used per cow for about 60 days.
The number of animals per acre or days of grazing may be maximized by intensive management with temporary fencing. Cattle may be given access to only a part of the field at a time and then moved according to speed of consumption. With the same number of animals, this might extend the overall residue grazing period of a field by several days. A good rule of thumb to assist in deciding when to supplement the cows or to move them is to watch for the disappearance of corn kernels in the manure.
When cattle are through with the better quality grain, husks, and leaves, which depends on the stocking rate and weather, supplementation or movement to a different field or pasture may be necessary. Protein is the limiting nutrient in residue grazing and the grazing period can be extended considerably with the side feeding of just 2 - 3 lbs. of soybean meal, 4 - 6 lbs. whole cottonseed, or 8 - 12 lbs high protein hay per head per day. Cattle being wintered on cornstalks should get a normal winter ration with hay or silage as well. The most deficient mineral and vitamin of residue are phosphorus and vitamin A, respectively. It is imperative to provide free choice minerals while cattle are on corn fields. The enemies of corn residue grazing are mud and extremely cold weather or snow. In North Carolina, mud may cause the maintenance energy needs of the cattle to be higher, decreasing weight gains.
While most common for weaned, late bred cows, corn residues may be utilized successfully in a variety of other production systems. Some researchers suggest that delaying weaning until after residue grazing is a more efficient use of resources since there is still a high protein supplement, milk, available to the calf. Others who are fall calving may wean calves early before grazing the dams on residues or provide creep supplements for the calves. In calf backgrounding operations, corn residues and minimal protein supplementation can produce 1 lb/day gains at minimal cost.
Start up costs associated with cornstalk grazing are few. Modern temporary electric fencing offers flexibility and is relatively inexpensive, considering it can be easily taken up and used year after year. Using a 20 acre, 1100 x 800 ft. field and grazing cows as a example, with $0.10/ft fencing, costs are about $378. If it takes about $500 to "get it all done," with 2 cows/acre for 30 days that's about $0.42/cow/day for the first year and even less after that. If winter feeding costs are $0.72/cow/day, the break-even point would be if winter feeding is reduced by about 18 days.
For grazing field, cutting rolls on the combine header should not be used. Ordinary straight or tapered rolls do not damage the residue as much. If fall tillage is normally practiced, fields closest to the cattle may be saved for grazing and then spring tillage.
The cost effectiveness and flexibility of grazing corn residues makes the practice an important potential feed source for cows or calves in the fall. In North Carolina, the compatibility with bermudagrass or fescue permanent pastures will provide more grazing options and help to decrease winter feeding costs.
1. "Ration Sheet for Cows," Animal Clinic, Hastings, NE.
2. Church, D.C., Livestock Feeds and Feeding, 2nd. ed. 1986.
3. Klopfenstein, Roth, Rivera, and Lewis. Corn Residues in Beef Production Systems, J. Anim. Sci. 1987. 65:1139 - 1148.
4. Neuman, A.L. Beef Cattle, 7th ed., 1977.
5. Nutrient Requirements of Beef Cattle, National Academy Press, Washington, DC, 1984.
6. Russell, Brasche, and Cowen. Effects of grazing allowance and system on the use of corn-crop residues by gestating beef cows. J. Anim. Sci. 1993. 71:1256-1265.
7. Ward, J.K. Utilization of corn and grain sorghum residues in beef cow forage systems. J. Anim. Sci. 1978. 46:831-840.