The recent high winds have caused 50 to 100 bushel per acre of corn on the ground. With this amount of down corn, these fields are like a feedlot with unlimited access to a full feed of corn, especially if there is no cross-fencing. It will take good management strategies to use these fields with livestock.
Grazing the field with weaned or yearlings would be the best option. With this much corn, consider a class of livestock that would benefit from the high energy available in the field and could gain weight (pounds) as compared to maintaining weight (cows that are gestating). Both weaned calves and yearlings are inexperienced at grazing corn residue and will likely slowly adapt themselves to the high grain diet. These calves will first graze the perimeter of the corn field and any grass waterways then finally find the residue and the corn. Calves will need to be trained to an electric fence and well-maintained perimeter fences will be important. Weaned calves and yearlings will need to be supplemented with protein. The supplement needs to contain an ionophore. Follow label directions when feeding the supplement containing the ionophore. This should help with acidosis/founder.
Grazing the fields with cull cows would also be an option. With fall pregnancy checking occurring now, there may be an option to purchase non-pregnant cows and put weight on them and sell in January of 2013. Good candidates to buy as cull cows are cows that appear healthy and are thin. Cows that are already a body condition score of 6 are not good candidates to purchase. Body condition score 6 cows are already fat enough for the cull cow market and have little room for muscle gain. Most cows will be experienced corn stalk grazers and will find the corn quickly and acidosis/founder will be a concern. Fill the cows up with hay before turning them out on these fields. Although cull cows will not need a protein supplement, consider a supplement that contains an ionophore. Again, follow label directions.
Consider not grazing pregnant cows in these fields unless the fields were pre-grazed with weaned calves, yearlings, or cull cows. When the eardrop gets to three to five bushel per acre, there would be less risk grazing with pregnant cows.
Limiting access by cross-fencing is always option. Cross-fencing and over stocking to limit daily corn intake may be an option. There are some producers that have used their center pivot as a mobile cross-fence. Limiting access, only letting livestock graze for a certain number of hours, then removing will take management and consistency.
Producers should probably expect some calves to founder even with excellent management.
Determining Excess Ear Drop in a Corn Field
Estimating the amount of corn left in a field helps producers determine a grazing strategy. An 8-inch ear of corn contains about .50 pound of corn grain, therefore 112, 8-inch ears would equal 1 bushel (1 bushel = 56 pounds). By counting the number of ears, the amount of corn can be estimated. If corn is planted in 30 inch rows, count the number of ears in three different 100 foot furrow strips and divide by two to give an approximate number of bushels per acre. Small ears and broken ears should be counted as half ears, while very large ears could be counted as an ear and a half. Repeat this process in three to four different locations is a field that has a lot of ear drop. Any amount beyond 8-10 bushels per acre will require a well-planned grazing strategy to ensure that too much grain is not consumed.
For additional information, please see the UNL Extension publication, Grazing Crop Residues with Beef Cattle
Source: Rick Rasby, Beef Specialist , University of Nebraska