AgWatch


Consider Grazing Cornstalks

DR. TERESA L. STECKLER

SIMPSON, ILL.
   Since many cattleman have been fighting the weather this season to produce hay, it may be prudent to think about alternative feed sources to make the existing hay supplies last longer. This would especially true if the long range forecast is correct – a very cold winter with ample snow.
   While driving through many counties from central to southern Illinois, I noticed that the corn is drying up and will be picked very soon. While many pastures are still very green, especially for this time of year, the lack of rain and searing temperatures for the past month have hampered regrowth. Many of these same fields have foxtail and other “weeds” that the cattle will consume.
   Cattlemen will find grazing corn stalks to be a great benefit to them. Removing the cattle will allow the fall regrowth and stockpiling of cool season grasses and reduce winter feed costs.
   The major expenses associated with grazing corn residue include rent (for residue grazing only), fencing, water development, freight, and labor. These costs must be included in the beef production enterprise, but even with these added costs it may be possible to significantly reduce winter feed cost for the cow herd.
   Before turning cattle out into cornfields it is important to know what and when herbicides have been applied to the corn fields. I suspect with the ample rain there will not be any herbicide residues, but cattlemen need to be cautious.
   Under most conditions, one acre of residue from a combined field can provide 30 to 45 days of grazing for a 1,200 lb pregnant cow; however, this can be quite variable. Strip grazing can extend grazing time and make the quality of the diet more uniform over the grazing period. By limiting access to only a small portion of the field, cattle are forced to consume residual corn and the high-and low-quality forage components of the residue. Generally, a single strand of electric fence is sufficient to control grazing.
   When determining the stocking rate and grazing time, consider the amount of residue that will be trampled and wasted in the grazing process.  Research indicates that cattle grazing a whole field will utilize only 20 percent of the residue. This percentage can be significantly higher when the fields are stripped grazed.
   The nutritional quality of grazed corn residue is quite high early in the grazing period: approximately 70 percent TDN and 8 percent crude protein. It then gradually decreases over time to approximately 40 percent TDN and 5 percent crude protein. This is a result of the cattle selecting the highest quality feeds first and a weathering, or leaching of nutrients, from the residue over time. Cattle will first consume any grain that remains in the field. Then they will shift their preference to leaves and husks and finally cobs and stalks.
   As the nutritional quality of the corn residues decreases, producers will need to provide supplemental protein. Without supplemental protein, the digestibility, or the percentage of the forage that can be digested, will decrease and the forage will not be able to meet the nutritional requirements of the animal. Protein supplementation will help the cow’s rumen microbial population digest the forage and provide nutrients to the animal.
   Corn residue is quite low in most minerals; especially calcium, phosphorus, and vitamin A. As a result, a well balanced vitamin and mineral mix should be provided free-choice. 
   Grazing corn residue brings a slight risk for digestive disturbances in the cattle. Nutritional disorders such as bloat, acidosis, and founder can occur. The risk for these conditions varies greatly with the amount of grain in the field. Proving cattle with increasing amounts of grain for 10 to 14 days prior to turning them out on corn residue will help alleviate this problem.
   Grazing corn stalks this fall will provide cattlemen with an opportunity to extend the grazing season and reduce winter feed costs. One acre of corn residue can provide 30 to 45 days of grazing for a mature, gestating beef cow. Cattlemen who do not raise crops should investigate rental agreements with neighboring corn producers. Happy grazing! ∆
   DR. TERESA STECKLER: Extension Specialist, Animal Systems/Beef, Dixon Springs Agricultural Center, University of Illinois
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