Management strategies for grazing cornstalks
October 20, 2017
Corn residue is a tremendous forage resource in Nebraska and is one of the state's competitive advantages for beef cattle production. There are 9 million acres of corn grown in Nebraska annually and 2 million beef cows. The residue from corn production could feed all of the state's beef cows through the fall and winter and still have residue left over!
The following are keys to successful grazing of corn stalks.
Identify the Quantity and Quality of Feed Available
Prior to starting grazing, the amount of feed available needs to be determined. A foundational number that determines the amount of grazing available is the bushel yield per acre. For each bushel of corn produced, there will be approximately 16 pounds of leaf and husk available for grazing. It is recommended to target grazing of half this available feed. The Corn Stalk Grazing Calculator is an Excel® spreadsheet that can be used to estimate, based on cattle size and corn bushel yield, the number of grazing days that can be expected per acre. The Corn Stalk Grazing Calculator is also available in the NUBeef cow-Q-late app.
Unless the corn field has experienced a lot of ear drop, there is usually less than a bushel of ear corn on the ground per acre. If more than 8-10 bushels of corn are on the ground, a management strategy to limit corn intake by cattle will need to be used. If cows have husk and leaf to select, they will consume a diet that is 52 to 55 percent total digestible nutrients (TDN) and about 5 to 5.5 percent crude protein.
Forage quality deteriorates over time. The rate of deterioration will depend upon weather conditions. Cool, dry weather conditions in the fall and winter will maintain quality for a longer period of time; while wet, warm, muddy conditions will result in a faster deterioration of leaves and husk. Cattle will select the grain and best quality forage first when initially turned into a field. As cattle continue to graze and remove the available husks and leaves, diet quality goes down significantly.
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Determine if Protein Supplement is Needed
When determining if protein and/or energy supplement is needed for cattle grazing corn stalks, it is important to identify the class of cattle and performance objective for the cattle that will be grazing. Mature, dry cows will maintain body weight, and may gain weight, on corn stalks when grain, husks, and leaves are available.
University of Nebraska-Lincoln research showed that March calving cows that were protein supplemented and those that were not protein supplemented grazing similar corn residue fields were similar in reproductive performance. Cows in both groups had a body condition score greater than 5.0 prior to calving (2009 Nebraska Beef Cattle Report: Effect of Winter Grazing System and Supplementation on Beef Cow and Progeny Performance). Cows grazed from mid-November to about mid-February each year and stocking rate was determined using the Corn Stalk Grazing Calculator. Cows were about a body condition score of 5.0 when they began the corn residue grazing period. Salt, mineral, and Vitamin A supplement was provided.
Other classes of cattle may require supplementation of protein and energy to meet desired levels of performance. The following are examples of three different classes of cattle and levels of estimated protein and energy needed.
First-calf heifers in the 90 days prior to calving will need protein and energy supplementation to meet nutrient requirements when grazing corn stalks. Feeding 3.5 lbs per head per day of dried distillers grains would meet this need.
Fall-calving cows will need additional protein and energy to meet nutrient requirements. Cows less than three months after calving will need 4.5 lbs. per head per day of a supplement that is at least 30% protein and 90% TDN on a dry matter basis. Feeding 5 lbs. per head per day of dried distillers grains would meet this need.
Weaned calves grazing corn stalks with a targeted gain of 1.0 lb. per day will need to be feed an energy and protein supplement. Research has demonstrated that dried distillers grains fed at 2 lbs. per head per day when calves are grazing corn stalks will usually meet this targeted level of gain.
Have a Plan for Weather Events that Limit Grazing
Deep snow and ice can severely limit the ability of cattle to graze corn stalks. Have a backup plan and other feed resources available to meet cattle needs when this occurs.
For more information on grazing crop residue, please see the Nebraska Extension Circular Grazing Crop Residue with Beef Cattle.