Cow-Calf Corner
    AMMONIATION OF LOW QUALITY FORAGE
      

    David Lalman

    Gerald Horn

    Ray Huhnke

    Larry A. Redmon
    Extension Beef Cattle Specialist Professor Animal Science Extension Agricultural Engineer Extension Forage Specialist
      Each year, an abundance of low quality roughages is produced in Oklahoma. The supply of low quality roughages is the result of many factors including: high precipitation during the haying season, late harvest dates, and drought. Crop residues, such as wheat straw, grain sorghum stover, and corn stover are other potential sources of low quality roughages that are not often utilized in beef cattle diets because of their low nutrient value. Still another source of low quality roughage has resulted from CRP (Conservation Reserve Program) land that is either coming out of the CRP program or haying that has been allowed to relieve drought situations. 
    Application of anhydrous ammonia provides an opportunity to substantially improve the nutrient characteristics of these roughages. Use of this technology has grown considerably in the past 15 years. In general, a stack of roughage is covered with a polyethylene sheet to create an air and ammonia tight seal. Anhydrous ammonia is injected into the stack and allowed to react with the roughage for one to four weeks. 
    Why Ammoniate? 
    When an abundance of moderate to high quality forage is available, there is little reason to consider ammoniation. Application of this technique will be most practical in years of drought, when little forage is available or when moderate to high quality forage is expensive. It is also beneficial in situations when there is some other incentive to bale low quality roughage. An example of this includes operations where the main objective is to grow a fescue seed crop. The fescue residue is often baled to remove the material from the soil surface in order to allow forage re-growth to occur. The ammoniation process serves to convert the residue by-product into a moderate quality roughage for cattle. 

    Ammoniation improves roughage nutritive value by: 

    • Increasing roughage digestibility 

    • Increasing roughage intake 

    • Increasing crude protein content 

    • Allowing storage of higher moisture roughage by inhibiting mold development 
     

    How does it work?

    The term "anhydrous" in anhydrous ammonia refers to the absence of water. When the gaseous anhydrous ammonia comes in contact with roughage, it combines with the moisture (water) in the roughage to form ammonium hydroxide. Plant cell walls are made up of complex carbohydrates consisting of three primary compounds; cellulose, hemicellulose, and lignin. Ammonium hydroxide is an alkaline compound, much like lye soap, and serves to: 
    • solubilize hemicellulose by breaking chemical bonds holding lignin and hemicellulose together; and 
    • partially break down the structure of cellulose by disrupting hydrogen bonds. This reaction causes a swelling of the fiber and allows cellulase (the enzyme responsible for cellulose digestion) better access to the fiber for digestion (Church, 1988). Following ammoniation, most roughages have a darker caramel-like color and a softer texture. 

    What roughages can be ammoniated?

    Any roughage that has low nutritive value is a good candidate for ammoniation. Table 1 shows examples of different roughages that have been ammoniated and the resulting changes in crude protein content, dry matter digestibility, and roughage intake. 

     

    Table 1. Results of roughage ammoniation trialsa. 
     
     
     
    % Crude Protein
    % D.M. Digestibility
    Increase In
    Roughage
    Untreated
    Treated
    Untreated
    Treated
    D.M. Intake
    Wheat Straw
    3.7
    9.7
    38.9
    48.0
    18%
    Corn Stover
    6.2
    11.0
    48.0
    56.2
    22%
    Milo Stover
    5.4
    16.8
    46.2
    61.3
    -
    Prairie Hay
    5.8
    14.7
    49.5
    58.2
    -
    Fescue Hay
    6.6
    14.8
    39.7
    57.7
    36%
    Orchardgrass Hay
    7.1
    14.2
    46.1
    54.3
    22%
    Switchgrass Hay
    4.5
    11.0
    43.3
    53.2
    3%
    a Adapted with modifications from Kuhl, Kansas State University, 1981. 
     

    Precautions

    Ammoniation of moderate and high quality forages can cause toxicity in cattle! 

    Restrict ammoniation to mature, low quality roughages. Ammoniation of high quality roughages, such as alfalfa, forage sorghum, hybrid sudan, small grain hays, or any moderate to early harvested grass hay (including both cool and warm season species), can lead to toxicity problems known as "crazy cow syndrome" or "bovine bonkers." Symptoms include hyperexcitability, circling, convulsions, and even death. 

    Toxicity is caused when cattle consume sufficient quantities of the toxic compound, 4-methylimidazole, which is formed when soluble sugars in the roughage react with ammonia. This compound passes through the milk to affect nursing calves, and in fact, nursing calves seem to be more susceptible to the toxicity than mature animals. Mature roughages have low soluble sugar content and represent little risk of toxicity problems. 

    To minimize the risk of toxicity: 

    • Do not ammoniate moderate or high quality forages 

    • Do not apply more than 4% ammonia on a dry matter basis 

    • Do not ammoniate roughage that has wet spots from recent heavy rains because ammonia will concentrate in these wet spots 

    To reduce the risk of calf toxicity, either refrain from feeding ammoniated roughage to cows with young calves or wait until the calves are at least one month old. 

    If toxicity does occur, immediately remove ammoniated roughages for several days and avoid working or exciting the cattle. 

    Exercise Extreme Caution When Applying Anhydrous Ammonia

    Exposure to anhydrous ammonia can cause blindness, lung damage, burns, or death. If you are exposed, immediately flush the exposed area with water for at least 15 minutes. Seek medical attention immediately after emergency first aid treatment. 

    To be safe using anhydrous ammonia, always: 

    • Wear personal protective equipment including a mask, goggles, gloves, long-sleeved shirt, long pants, and proper work shoes. 

    • Have an ample water supply close by. 

    • Regularly inspect hoses and valves and replace them as needed. 

    • Be careful not to fill a tank over 85 percent of capacity. 

    • Bleed off hose pressure before disconnecting. 

    • Stay clear of hose and valve openings. 

    • Follow regulations when using equipment. 

    • Have a qualified technician repair the tank. 

    • Use the proper hitch, safety chains, and a Slow Moving Vehicle sign when towing. 

    For additional information on safe handling of anhydrous ammonia, see OSU Fact Sheet No. 1723, Anhydrous Ammonia. 

    To learn the details of ammoniation of low quality roughages read OSU Fact Sheet No. 2243.  You are strongly encouraged to  read this fact sheet closely before attempting the ammoniation process!
 
 
 

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