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Understanding Your Feed Analysis Report

August 25, 2020

by Scott Derring, Beef Field Technical Support

Beef cattle are more productive and efficient when fed a ration balanced based on their nutritional needs.  Nutritional values of feedstuffs vary widely due to several factors such as harvest/maturity date, soil type/location, storage, and other management practices.  Due to these variations, laboratory analyses of feedstuffs are critical to providing reliable nutritional information to not only balance rations, but also to determine the most economical ration.

Feedstuffs can be analyzed using two common methods, near-infrared reflectance spectroscopy (NIRS) and wet chemistry.  NIRS is a computerized method that uses light reflection rather than chemical evaluation to estimate nutritional value.  The estimation of nutritional value via NIRS is driven by wet chemistry analysis.  Meaning, the accuracy of NIRS is dependent upon the feedstuff being previously well-characterized by wet chemistry.  Therefore, when using the NIRS method, it is necessary for the laboratory to have an extensive wet chemistry database on the particular feedstuff being analyzed to ensure accurate estimation of nutrient(s).  Additionally, the NIRS method may not accurately evaluate a full mineral profile of a feedstuff.  While NIRS is a valuable tool, sometimes the wet chemistry method is a better option.  Wet chemistry is considered the gold standard for feed analysis.  Wet chemistry is the preferred method for mineral content, in particular trace minerals, and is required for analysis of TMR’s.  However, due to labor, time, and materials, the cost and turn-around time for wet chemistry is greater than for the NIRS method.

Each laboratory will have several test packages to choose from, depending on what nutrient(s) you want to be tested.  A typical lab analysis report will provide dry matter, protein, fiber measurements, macro and some micro minerals, fat, and energy calculations.  When submitting corn by-products for laboratory analysis, make sure that sulfur and phosphorous are included in the test package chosen to ensure your ability to monitor those levels in the final diets for cattle.

Crude protein measures the nitrogen content of feedstuff and calculates that value by multiplying it by 6.25, as protein is made up of approximately 16% nitrogen (100/16=6.25).  Many labs will characterize the protein fraction that is degradable in the rumen, called degradable intake protein (DIP), and the fraction of protein that is undegraded in the rumen, undegradable intake protein (UIP).  Supplements supplied by Quality Liquid Feeds are an effective and efficient way to deliver non-protein nitrogen (NPN), a form of DIP, to your cattle rations, ensuring adequate nitrogen is available for the rumen microorganisms to synthesize bacterial crude protein.

Energy can be expressed in several ways, including total digestible nutrients (TDN), net energy (NEm, NEg or NEL), digestible energy (DE), or metabolizable energy (ME).  For beef cattle diets, the Net Energy System (NEm, NEg or NEL) is commonly used for diet formulation.  It is important to know that an equation is used to calculate net energy values, as it cannot be quantified through chemical analysis directly.  There is not a standard equation that all laboratories use to calculate net energy values, making it difficult to interpret energy values between labs.

Regardless of the method or lab used, it is important to test your feedstuffs.  We would recommend using the same lab as much as possible to ensure consistency of analysis and results from year to year.  If you have any questions or need assistance developing balanced diets for your cattle, please contact your local QLF Representative.

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