Livestock · March 2025 · 5 min read
A hay test removes the guesswork from livestock nutrition by quantifying protein, energy, and fiber in every cutting. Understanding what each number means helps you match hay quality to animal requirements and avoid over- or under-feeding expensive supplements.
Crude protein (CP) indicates nitrogen content and typically ranges from eight to twenty-two percent in grass and legume hays. Acid detergent fiber (ADF) measures the least digestible fiber fraction—lower ADF means higher energy. Relative feed value (RFV) combines ADF and neutral detergent fiber into a single index, with 100 representing full-bloom alfalfa as the baseline.
Use a hay probe or core sampler to collect cores from at least twenty bales per lot for a representative sample. Sample from the side of round bales or the butt end of square bales, avoiding weathered outer layers. Send samples to a certified forage testing laboratory and request the standard forage analysis package.
Lactating dairy cows need hay with an RFV above 150 and crude protein near eighteen percent, while dry beef cows perform well on hay with an RFV around 90. Growing heifers and stocker cattle fall between these extremes, needing moderate protein and energy to maintain target gains. Testing allows you to allocate your best hay to animals with the highest nutritional demands.
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