Nitrate warning for cattle feed – high levels detected locally – CSU offering testing

Nitrates and Feeding Cattle

Fall has come to Southeastern Colorado and winter will soon be here. This finds many livestock producers gathering hay or stubble leases to carry their livestock through the cold months. Although the area had a good summer with adequate precipitation and low stress on crops I have had and heard reports of livestock feed testing high in nitrates. It is advised that livestock producers test potential feed bales or grazing stubble for nitrates. With the higher-than-normal prices of cattle, testing feed is another tool to protect your investment.

Forage samples can be brought into the extension office and be given an initial diphenylamine test. A few drops of the diphenylamine solution are placed on the sample and observed for a dark blue or purple color change. The change of color can indicate the presence of nitrate over a level of 5,000 part per million. When results show positive (blue color), the forage needs to be sent to laboratory for a quantitative analysis before feeding.

Understanding the results of a quantitative analysis by a competent laboratory is imperative. Results are based on samples provided for testing. To achieve accurate test results, samples need to be taken from various parts of the field or multiple bales of hay. This test will give a quantitatively averaged result from the sample provided. Producers should understand there could be outlier plants, parts of the field or bales that are higher in nitrate than the results show.

Caution should always be used when making feeding and grazing decisions of sample test results showing the presence of high nitrate levels. While making these feeding decisions the total amount of nitrates in feed and water need to be considered. If a feed sample doesn’t test high, it can be used to help lower the nitrate level of a diet. Knowing the level of nitrates in all feedstuffs used in a ration is your only way to build a safe ration to feed.

There are three types of commercial laboratory tests for forage nitrates. The nitrate (NO3) test shows parts per million (ppm) of nitrate and is the easiest to interpret. The other two commercial tests provide some slightly different numbers. Nitrate-nitrogen (NO3-N) and potassium nitrate (KNO3) tests gives different result numbers but can be converted to equate to the nitrate (NO3). Colorado State University Range Extension has a calculator that can be used to make the conversions. It can be found at: www.range.colostate.edu/nitratecalc.shtml.

Colorado State University Extension has the following recommendations based on the results of a nitrate (NO3) test:

Nitrate Level (Maximum) Recommendations Based on the Maximum Nitrate Level

For more information on nitrate testing of forage and nitrate poisoning of livestock visit

CSU Fact Sheet No. 1.610 – Nitrate Poisoning at https://extension.colostate.edu/topic- areas/agriculture/nitrate-poisoning-1-610/

Tearle Lessenden Kiowa County Ag/Natural Resources, 4-H Specialist Email: tearle.lessenden@colostate.edu Phone: 719-438-5321