Corn Stalk Grazing; A Perfect Fit for Spring-calving Herds

Published on Wed, 08/02/2017 - 12:50pm

 Corn Stalk Grazing; A Perfect Fit for Spring-calving Herds

 By Daniel Herold, Ph.D., Manager Beef Nutrition and Technical Services

 Dry days of early fall initiate the end of summer grazing for spring-calving herds in the Midwest and northern plains.  With pastures nearly spent, the total intake needs of cow-calf pairs grows each day to fill the rumen of rapidly-growing calves and sustain late-season lactation.  Timely rains may arrive to support regrowth, but can only temporarily delay the countdown to weaning.  Fortunately, when one door closes another is opened with the appearance of combines and the advent of harvest.  The remaining crop residue is a resource that closely matches energy needs of the spring-calving cow after weaning, and allows grazing to continue long after pastures have gone dormant.

Grazing cornstalks yields benefits from both nutritional and economic perspectives.  For the cattleman, the expense required to produce the crop; fertilizer, herbicide, equipment, etc., is applied to the grain enterprise rather than forage production.  Additionally, each day of grazing through fall and winter reduces the annual expense of purchased feed.  Consider that for each month 2.5 cows continue grazing, one ton of hay is spared.  Reducing days that cows are in dry lot saves yardage and equipment costs associated with feeding and spreading manure.  For the farmer, cattle will minimize the amount of volunteer corn in corn-bean rotations, and manure is more nutrient dense and easier to incorporate into the soil than crop residue.
The term “Corn Stalk Grazing” is actually a misnomer given that cattle selectively graze the available grain, husk, and leaves first, and only resort to stalks and cobs after the more digestible feed is gone.  Before cows are observed actively chewing stalks, it is time to move to a new field or initiate a feeding plan, as there is limited supply of good-quality forage remaining.  Husks and leaves are very digestible and palatable, and can have a higher energy content than mature grass hay.  Both baled hay and baled corn stalks contain the stem or stalk portion of the plant.  These structural components contain more fiber and less energy than the husks and leaves, and dilute the energy content of mechanically-harvested forage relative to grazed corn residue.
Nutrient contents of grazed corn stalks fit the energy needs of dry cows during second trimester quite well, but supplemental protein, vitamins, and minerals are required.  The grazed portion of crop residue can average 50 to 55% TDN (32 NEg, 58 NEm) in fresh stalk fields, which is adequate energy for cows in acceptable body condition post-weaning.  Thin cows will readily gain weight with a little additional energy.  Protein in stalks is lower than the cow requirement, ranging from 3 to 6%.  Fetal programming research demonstrated the importance of protein supplementation during the second trimester, but the primary benefits are manifested in the developing fetus and future calf, rather than in the supplemented cow.  While no improvement in conception rate was noted when cows grazing crop residue received protein supplementation, calves from these cows exhibited a tendency for enhanced quality grade and pregnancy rate (Funston, et al., 2009 Nebraska Beef Cattle Report, pp. 5-8).  Additionally, vitamins and trace minerals in crop residues are below adequate levels and need to be supplemented.  A very effective and simple means to deliver required protein, vitamins, and minerals is by supplementing with CRYSTALYX® brand low-moisture blocks.  There are several options to choose from ranging in protein from 20 to 40%.  Cows will consume around 1 lb. per day, obtaining their protein needs from one convenient package.  Provide one CRYSTALYX® block per thirty cows.  Be sure to also provide salt to complete the CRYSTALYX® program.  STOCKMASTER® Mineral may also be provided along with the CRYSTALYX® low-moisture blocks as a source of salt, to enhance vitamin and mineral supplementation, or to address deficiencies and antagonists by providing organic trace minerals.
Minimal management is required to maintain cows on corn stalks, but some important aspects should be considered in advance:

Fence and water: For remote fields, electric fence works well when enough forage is available to keep cows content.  Water may need to be hauled and kept open in winter.  Cows can drink from 1 to 2 gallons of water per 100 lb. of body weight depending on the ambient temperature.  When fields are adjacent to an existing feedlot pen, water is easily accessible and cattle can be fed in the event of inclement weather.
Stocking rate: Carrying capacity of corn stalk residue can be derived from the grain yield of the crop using the University of Nebraska Corn Stalk Grazing Calculator.  In general, approximately 8 lb. of edible residue is available per bushel of corn.  Therefore, it is typical to run one 1400 lb. cow per acre for 30 to 40 days, or one 600 lb. calf per acre for two months.  Plan to remove cattle from corn fields based on regional timing of spring thaw and frost leaving the ground to avoid soil compaction, trampling feed, and formation of mud holes around water tanks.
The best grazing is right after harvest: Assuming fields are dry, grazing soon after harvest ensures the most abundant and best-quality forage versus delaying turn-out.  The longer crop residues go without being grazed increases the risk of wind loss, snow cover, rain and possible mold contamination, decomposition, and soil accumulation on the feed.  Keep in mind that with each day of grazing, the quality of the remaining forage declines due to trampling, manure, weather-related loss, and because cows instinctively eat the best-quality feed first.
Before turn-out: Fields should be checked for piles of corn spilled during harvest.  Remove this grain to avoid risk of over-eating and acidosis.  Feed cattle to fill before turning out to lessen the abrupt diet change and reduce stress.  Look for hazards in fields where cattle are not typically maintained such as dump areas, loose wire, and large culverts that could allow cattle to escape.  Fence off these areas along with irrigation equipment and other structures/items susceptible to damage.  Ensure electric fence is intact and has good current.  Deer often knock wire off insulators between the time when fence is put up, and cattle turned out.  A hot wire is especially needed in the first days as cattle establish their new boundaries.  In times of drought, stalks should be tested for nitrate content prior to turn-out.  The highest concentration of nitrate exists in the lower portion of the stalk.  Be sure to move cattle to a new field at the appropriate time as this is typically the last part of the plant consumed.
Special considerations for grazing calves: Moderate-framed calves wintered on corn stalks can gain between .75 to 1.00 lb. per day depending on forage and grain quantity, and weather stress.  The best approach to managing calf nutrition on stalks is to have bunks established to allow supplemental feeding.  Calves will need additional protein, and vitamin/mineral supplementation while grazing stalks.  This can be delivered via TMR, protein pellets, or grain and protein mix fed daily.  Additional energy may also be required to reach a specific gain that the stalks alone will not support.  Coccidiosis prevention (either Rumensin®, Bovatec®, or Deccox®) should be provided daily in the supplement to avoid an outbreak.  Bunks are also a part of a plan to feed calves in the event of snow cover, or to maintain calves on the field after the crop residue is consumed.  Access to a working facility should also be considered to treat respiratory disease and other common ailments such as bloat, foot rot, and pinkeye.
Corn stalks can provide an economical means to extend the grazing season, delay winter feeding, and meet the energy needs of the second-trimester cow or backgrounding calf with minimal input and management.  While many stalk fields fall prey to the disc or are left idle for erosion control, those that are grazed are a perfect fit for the spring-calving herd, and quite effectively convert the fiber we can’t use into the beef we all enjoy!