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Forage Nutrition Nitrates

Timothy and Alfalfa Hay Blog

    Forage Nutrition 101: Nitrates

    Posted on May 19, 2016

    Quality forages are vital to the livestock industry, as only the top quality options provide crude protein, acid detergen/neutral detergent fiber, minerals, and other nutrients essential to animal health. Forage quality depends on a variety of conditions, such as the harvesting process, soil, fertilization, maturity – factors that impact both the physical characteristics and chemical makeup of the final product. Premium forages aren’t developed overnight; they are the result of extensive expertise and years of experience.

    When assessing forage options, one measurement commonly used to measure quality is the percentage

    of Nitrates it contains, as too high levels can cause serious health issues for livestock – or even death. This blog includes basic information on this component of various feeds, including details on percentages and why levels are so important.

    What are nitrates in forages?

    Nitrates are found naturally in soil and can make their way into forages through the roots of certain plants, known as accumulating plants. They arere also added to man-made fertilizers because of  their high solubility and quick biodegradability. The two most common ways of analyzing nitrates levels in forages are:

    1. To report nitrate ion levels as a percentage; OR,
    2. To report nitrate nitrogen in parts per million (ppm).

    Nitrates levels present in forages have less to do with the amount that is actually in the soil as they do the environmental conditions in which the forage is grown. The amount of nitrates that build up in forages also depends on the plant species, maturity and which part of the plant they’ve accumulated – i.e., stalk or stem, leaves, roots.;

    How do nitrates levels vary?

    Nitrates levels can reach toxicity in forages any time the nitrogen supply in the soil exceeds the nitrogen needs of the plant. Plants absorb nitrogen from the soil in the form of nitrate, which is later converted to protein. When nitrate is present in the forage and protein synthesis is slow, nitrates will accumulate until the rate of protein synthesis increases.

    Nitrates accumulate in the stalk of plants at high levels when certain environmental factors are present, such as:

    • Shading or low light levels;
    • Extreme weather, including drought, early frost, hail or cold;
    • Improper herbicide application; and
    • Disease.

    Anything that slows down the rate of plant growth can lead to increased nitrate levels in well-fertilized plants.

    Why are nitrates important?

    The level of nitrates in forages can be deadly for livestock. Nitrates go through a transformation when consumed by livestock, as they are changed first to nitrites and then to ammonia before being expelled in urine. The intermediate byproduct – the nitrites –are the cause of toxicity. At higher levels, nitrite can be absorbed into the bloodstream and interfere with blood cells that carry oxygen from the lungs to bodily tissues. The animal will die if the oxygen carrying capabilities of blood are reduced. Levels of nitrates in forages may not be an issue if consumed over a few days, but they can be very harmful if the animal feeds over a few hours.

    Based on both of the approaches to measuring nitrates levels in forages, here is some guidance on feeding for livestock:


    Nitrates levels are just one of many components that impact forage quality;Acid or Neutral Detergent Fibers, Phosphorus, and Crude Protein are other details you’ll need to consider when choosing a premium product.  They are all covered in our Nutrition series we are blogging; subscribe to our blog to receive notifications when we post new information!  

    Topics: Alfalfa Hay, Quality of Forage, Timothy, Horse Nutrition, Export Hay