Grazing Corn Residue

Corn Residue: A Resource for Graziers

                        Rory Lewandowski, Extension Educator Wayne County

            For every bushel of corn harvested by the combine, there is between 14 to 16 pounds of corn residue dry matter left in the field.  Graziers need to view that residue as a resource opportunity.  In recent years, between 3.3 to 3.6 million acres of corn have been harvested for grain in Ohio.  The remaining corn residue on those acres is composed of corn grain, cob, husks, leaves, and stalks, all of it with some nutritional value.  Corn residue, when grazed during a mid-October through December time frame is a suitable feedstuff for most classes of ruminant livestock.  The exceptions are livestock in a late gestation or lactation stage of production.  In addition to using a low cost feedstuff, grazing corn residue removes animals from grass pastures during the late fall period.  This can benefit pastures, insuring that they are not overgrazed before they go dormant.  Grazing corn residues can help to stretch stockpiled forages so that they are not used until later in the year.   

            The nutritional value of corn residue varies depending upon how the residue is grazed, the amount of time that has passed between harvest and grazing and environmental conditions.  According to a South Dakota State University Extension publication entitled “Grazing Corn Stalks” a crude protein (CP) content of 8% and a total digestible nutrient (TDN) content of 70% can be expected early in the grazing period.  Over time the nutritional content will decrease to 5% CP and 40% TDN.  This is a typical pattern where livestock are provided with an entire field or a large section of a field and allowed to graze over an extended time period of 30 to 60 days. The nutrient content decreases because livestock are selecting the highest quality, most palatable portions of the residue first and because nutrient content decreases as the residue weathers and soluble nutrients are leached out. 

The University of Nebraska has done a lot of research on the topic of grazing corn residue.  A University of Nebraska study conducted over a 5 year period from 2004 to 2009 measured corn grain left in the field after harvest.  An average of 1.0 bu/acre was available for livestock grazing.  A 2004 Nebraska beef report on corn stalk grazing included more information about the make-up of corn residue.  Generally, stalks account for 49% of the residue dry matter, leaves 27%, husks 12% and cobs another 12% of the residue dry matter.  Livestock typically consume any corn grain first.  After the grain, plant leaves and husks are eaten and the last portions of residue eaten are cobs and stalks. Strip grazing across a field can even out the nutritional quality because livestock will be forced to consume both the higher and lower quality components of the residue within a given grazing period before the fence is moved to provide a new strip.  A 2004 Nebraska beef report on corn stalk grazing listed the average TDN value at 54-55%.

            Now let’s look at an example of how corn residue can be used. The general rule of thumb that is used is; one acre of corn residue will provide grazing for one mature cow for about 45 days.  Often that cow is defined as one animal unit or 1000 lbs.  Most cows are heavier than that so those thumb rule grazing days are less in most instances.  If corn yield is 150 bushels per acre, we might expect somewhere around 2250 lbs. of total dry matter residue.   Not all of that dry matter residue will be consumed.  University of Nebraska research on the effect of stocking rate on animal performance and diet quality while grazing cornstalks demonstrated that very little if any of the corn stalks are eaten.  The study measured the amount of each component of corn residue consumed as a percentage of the total dry matter consumed by cattle.  After corn grain, leaves and husks accounted for 71 to 88% of the total residue consumed and cobs contributed up to another 23%.  Overall the study found that less than one-third of the total residue material available was actually removed from the field.  The University of Nebraska has a corn residue grazing calculator available on-line at: http://beef.unl.edu/learning/cornStalkGrazingCalc.shtml that can calculate the number of acres of corn residue needed for a desired number of grazing days based on corn yield and cow weight.  It will even provide some economic analysis depending upon figures entered into the calculator. 

            Livestock in mid-gestation and even into the third trimester of gestation can do well on corn residue without additional supplementation provided they are not forced to begin eating the actual corn stalks as a significant portion of the diet.  A 2012 Nebraska Beef Cattle Report included the topic of “Supplementing Gestating Beef Cows Grazing Cornstalk Residue”.  This was a 5 year study that evaluated the effects of protein supplementation to beef cows grazing corn residue in late gestation.  The study concluded that “supplementing cows grazing corn stalks in mid to late gestation did not improve cow reproduction or calf performance.  Protein supplementation is not necessary for cows grazing cornstalks, given they begin the grazing period in adequate body condition (BCS greater than or equal to 5).”

            Occasionally I hear some misgivings that livestock can no longer get the same performance from the genetically modified corn residues compared to the non-genetically modified varieties.  This topic has been investigated.  The 2004 Nebraska beef report included results from a study that used steer calves grazing four different fields of corn residue for 60 days. The four fields were residue from a Bt corn rootworm variety, a non Bt variety, a Roundup Ready (RR) variety and a non RR variety.  The conclusion was steer performance was not different between Bt corn or RR hybrids and their non-genetically modified variety controls.  The same study concluded that “there was also no preference between Bt and non Bt hybrids” during the grazing period.

            Some crop farmers may be wary of letting a neighbor’s livestock graze across a field because of concerns about possible negative impact on the yields of subsequent grain crops.  This subject has also been researched at the University of Nebraska in a series of multi-year corn residue grazing studies using various stocking densities.  The conclusion as reported in the 2013 Nebraska Beef Cattle Report was that “…corn grain yields in either a continuous corn or a corn-soybean rotation show no effect of grazing on grain yields and soybeans planted the year following corn residue grazing show a significant increase in yields due to grazing treatment.”

Corn residue represents another opportunity to extend the grazing season. Those graziers willing to find a way to use corn residues by developing relationships with crop farmers, utilizing temporary fencing and water can reduce the amount of stored forage needed for winter feeding and reduce production costs.

University of Nebraska beef cattle reports can be found on-line at: http://beef.unl.edu/web/beef/reports .

North Central Ohio Dairy Grazing Conference January 23 and 24, 2014

North Central Ohio Dairy Grazing Conference will be January 23and 24, 2014 at the Buckeye Event Center in Dalton, Ohio. Mervin Hershberger, dairy grazier from Winesburg, Ohio, will talk about “Walnut Acres Farm”. Other speakers will be Doug Gunnink from Gunnink Forage Institute out of Minnesota,  Pennsylvanian veterinarian Hue Karreman and Dr. Geoff Brink, agronomist, with US Dairy Forage Research Center in Madison, Wisconsin.   Anthony Steffen and David Yutzy are Ohio dairy graziers who will share their farming experiences. A panel of veteran dairy graziers will give advice on “Troubleshooting Farm Issues”.    The young farmer panel will feature 4 dairy graziers sharing their experiences. Breakout sessions will be on crop rotation, soils, forages, mastitis and other dairy health issues.  This two day program is full of information and opportunity to network with dairy graziers across Ohio and the Midwest as well as vendor show. The cost for the conference is $55 for the two days.  Registrations are due by January 16, 2014.  For a brochure or more information, contact Leah Miller at Small Farm Institute, P.O. Box 214, Millersburg, OH 44654 or email leah@smallfarminstitute.org.

Gallia-Lawrence Grazing School

The Gallia-Lawrence County  Grazing School is scheduled for Wednesday night November 6, 2013 6:00 – 9:00, Thursday evening November 7, 2013 6:00 – 9:00 and Saturday morning November 9, 2013 9:00 – 12:00.  The Ohio Forage and Grassland Council, NRCS, and the Gallia and Lawrence County Soil and Water Conservation Districts (SWCD) will be hosting a Pasture Management Workshop/ Grazing School/ Pasture for Profit Program at the C. H. McKenzie Agriculture Building, 111 Jackson Pike, Gallipolis, Ohio 45631. 

The sessions will cover setting your goals and objectives, evaluating your resources, understanding plant growth, grazing economics, and forage species selection, conservation practices, developing contingency plans for drought and mud, soil pasture fertility, fencing and livestock watering systems.  When the landowners finish the course, they will have developed an assessment to complete a Grazing Management Plan for their operation.  The Grazing Management Plan will outline the conservation practices and management needed on your farm to improve forage production and animal performance in a way that also protects the environment.  This grazing management workshop is designed to help livestock producers improve their livestock operation and grazing management system.

Producers need to register by October 29, 2013 by contacting the Gallia County SWCD at 740-446-6173.  A registration fee of $10 will include materials, Pasture for Profit notebook, Pasture Stick, and refreshments. 

The program will provide valuable information in a fun atmosphere that can be used to ensure that the grazing operation on your farm is environmentally responsible as well as economically viable.  If you are a farmer or a person with an interest in grazing management-pasture ecosystems plan to attend.  The benefits from attending include additional points in the USDA-Natural Resources Conservation Service  EQIP (Environmental Quality Incentives Program) ranking process, increased knowledge about forage plant growth, improvement of the environmental quality; cleaner air and water; healthier soil, plant and animals.  Learn ways to increase net profit for your farming operation.

Meigs County Grazing School

The Meigs County Soil and Water Conservation Districts, Ohio Forage and Grassland Council and NRCS  will be hosting a Pasture Management Workshop/ Grazing School/ Pasture for Profit Program at the Kountry Resort Campground located at 44705 Resort Road, Racine, Ohio 45771.  The Grazing School will be Tuesday October 29 and Thursday October 31, 2013 6:00 to 9:00 pm concluding Saturday November 2, 2013 starting at 9:00AM and ending at noon.  Saturday will be an outside pasture walk and farm visit.

The sessions will cover setting your goals and objectives, evaluating your resources, understanding plant growth, grazing economic, and forage species selection, developing contingency plans for drought, mud and deep snow, soil pasture fertility, fencing and livestock watering systems. 

Producers can register by contacting the Meigs County SWCD office at 740-992-4282, or email steve.jenkins@oh.nacdnet.net.  A registration fee of $40 per farm will include materials, Pasture for Profit notebook, Pasture Stick, and refreshments.  Additional registrants from the same farm are only $10. 

The program will provide valuable information in a fun atmosphere that can be used to ensure that the grazing operation on your farm is environmentally responsible as well as economically viable.  If you are a farmer or a person with an interest in grazing management-pasture ecosystems plan to attend.  The benefits from attending include additional points in the USDA-Natural Resources Conservation Service  EQIP (Environmental Quality Incentives Program) ranking process, increased knowledge about forage plant growth, improvement of the environmental quality; cleaner air and water; healthier soil, plant and animals.  Learn ways to increase net profit for your farming operation.

QUALITY CORN SILAGE PRODUCTION

Rory Lewandowski, Extension Educator Wayne County

Corn silage has the reputation as a reliable and economic feedstuff.  Corn silage is widely used in ruminant livestock rations, particularly with cattle, but I have also seen it used with sheep as well.  A good thought to keep in mind is that the quality of the corn silage you produce this fall will affect your livestock for many months in to the future.  Producing high quality silage depends upon good management practices at several different steps.

            Corn silage is a fermented product.  To be effective that fermentation must take place in an anaerobic (no oxygen) environment.  The goal in this fermentation process is to achieve a pH of less than 4.0.  This can be accomplished when air is removed as quickly as possible after chopping so that high concentrations of organic acids, predominantly lactic acid, are rapidly produced.  This may sound simple, but implementation depends upon good decisions, harvest preparation, and some cooperation from Mother Nature.

            The first and most critical step is that corn must be chopped at the right moisture or dry matter (DM) content.  If you don’t get this right, nothing else will matter.  A DM range of 30-38% is acceptable.  Silage put into a bunker silo should be at the lower end of this range while silage put into upright silos should be at the upper end.  Corn less than 27 to 30% DM does not ferment properly.  It produces silage that often has high concentrations of butyric acid and can have a very low pH.  This silage will have an unpleasant odor and animal DM intake will be reduced.  Corn chopped at higher than 40% DM does not pack well.  As a result it usually does not ferment adequately, resulting in low acid concentrations, heat damage and moldy silage.  Starch digestibility is usually low, causing the silage to have less energy.   Silage harvest needs to start on the wetter end of the acceptable range because corn will gain DM content or lose moisture at a rate of between 0.5 to 1.0 percentage points per day.  Rapid harvest is important to ensure that corn is chopped within the acceptable moisture range.

            Chop length is a consideration for silage packing, feeding and animal performance.   A three-eighths inch (3/8) theoretical length of cut (TLC) is recommended for corn at 32 to 36% DM.  When DM is under 32%, a three-quarters (3/4) inch TLC is recommended and when DM content is above 36%, a TLC of less than 3/8 inch is recommended.  There is a reason that this is termed “theoretical”.  The actual cut length in the field can vary so operators should look at the actual chopped forage and make adjustments to get the correct chop length.  One practice that can change these recommendations is kernel processing.  Kernel processing involves fracturing the corn kernels as the corn plant is chopped.   Research results have consistently shown benefits in animal performance when kernels are processed adequately.  The goal is to crack 90 to 95% of the kernels and 70% of those should be fractured to smaller than one-quarter of a kernel.  When kernel processing is a part of the chopping process then TLC is typically increased to three-quarters of an inch.

            One question that often comes up in any silage production discussion is whether or not to use a silage inoculant.  There are 2 main types of inoculants; homofermenters and heterofermenters.  Homofermenters contain Lactobacillus bacteria that produce lactic acid and heterofermenters contain Lactobacillus buchneri that produce lactic and acetic acid.  The lactic acid promoting inoculants are used to increase silage quality by driving the silage pH down quickly and reducing DM loss during the fermentation process.  Dry matter loss during fermentation is higher with the buchneri type inoculants but feed out losses can be reduced.  The buchneri inoculants are used to increase the aerobic stability of silage during feed out.  The acetic acid produced prevents yeast growth.  Bill Weiss, OSU dairy nutritionist located at the OARDC in Wooster says that his standard recommendation regarding inoculant choice is that if you have historically had problems with moldy silage during feed out or if the TMR ration gets hot in the bunk, then use the buchneri type.  If neither of these is an issue, then use the lactic acid promoting type of inoculant.  Regardless of which inoculant type is used, the key is to purchase high quality inoculants and to apply them correctly.

            After DM content, the next critical step is the rapid removal of air by packing.  As layers of forage are added to the silo or pile, they need to be driven over multiple times by heavy machinery.  The goal is to achieve a silage density of 15 lbs. of DM/ft³ or higher.  The density is directly correlated with oxygen exclusion within the silage pack and generally high silage density results in lower DM losses.  The guideline for packing is that 800 pounds of packing weight is needed for each ton of silage delivered to the silo or pack.  For example, if the harvest rate is 50 tons/hr. then the packing weight needed is 50 x 800 = 40,000 lbs. or 20 tons.  In addition to the packing weight, the thickness of the layer packed should be monitored.  The optimum condition is to pack layers of 6 inches or less.  Another piece of advice from Bill Weiss regarding packing is: If you think you have packed enough; pack some more.

            The final important step is covering the bunker or silage pile.  This should be done as soon as the bunker is filled and the final packing had been done.  Covering prevents oxygen, weather and animals from getting into the silage pack.  Covering reduces DM and spoilage losses.  The recommendation is to cover with plastic of 6 to 8 mil thickness and weigh that plastic down, sealing the edges as well.  University research trials have demonstrated that the oxygen barrier 2-step products have reduced losses more than covering with the 6 to 8 mil plastic.