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The Cattle Connection

Fall is the time for cattle producers to sample and interpret hay forage tests

cows eating hay

Cooler temperatures and fall leaf foliage are reminders that winter is just around the corner. For cattle producers, this reminder also brings fewer grazing days and the need to focus on winter rations for beef cows. The foundation of a least-cost, balanced winter ration starts with a forage test. For those buying or selling hay, forage testing can play an even bigger role in pricing and purchasing value. Fall is an ideal time to test, as it will allow enough time to price and plan for winter feeding.

Sample in lots

A ‘lot’ is defined as forages from the same field, harvested at similar times, and is handled and stored in the same way. Forage quality differs between cuttings. Identify different cuttings and separate fields to allow for uniform lot sampling.

How to Sample

To obtain the best representative sample, use a hay probe/core sampler that is at least 12 inches long and 3/8-5/8 inches in diameter, with a sharp edge.

  • For round bales, insert the probe through the rounded edge of the bale. Randomly sample 15 to 20 bales, depending on the lot size.
  • For square bales, sample from the square end. Randomly sample at least 10 bales, making sure to sample different sides throughout to account for storage differences.

Place samples in a sealed plastic bag. Store in a cool, dry environment until analysis can be done. Label the bags with your name, address, lot identification, and date. It is important to send the sample as soon as possible to avoid drying out and altering of results. If possible, sample and send early in the week to avoid any weekend delays.

A standard test should be sufficient to understand forage quality. The key results will be moisture, protein, and energy. Consult your nutritionist or feed supplier to ensure results allow least-cost, balanced ration formulation.

Interpreting results

Interpreting results can be daunting, but spending some time going through sample results will prove to be beneficial.

Key definitions and abbreviations

  • Dry Matter (DM): The percentage of a sample that is not water. This will allow comparison between feedstuffs. 85% is ideal for dry hay.
  • Acid Detergent Fiber (ADF): A measure of the least-digestible plant carbohydrates. Higher ADF would be correlated with less digestibility. Lower numbers indicate better digestibility.
  • Neutral Detergent Fiber (NDF): Inversely correlated to intake potential. Higher NDF would mean lower forage intake potential.
  • Total Digestible Nutrients (TDN): Energy value of the forage. The greater the value, the higher the energy. Less mature forages will have higher TDN. As ADF and NDF increase, TDN decreases. Throughout life stages, cattle will have different energy requirements. A dry cow will require near 48% TDN whereas a lactating cow will require 60% or more.
  • Crude Protein (CP): An estimate of protein content. This is calculated using the nitrogen content, which is highly dependent on forage species and maturity. In a beef herd, protein requirements are dependent on stage of life and lactation. A lactating cow will have a higher protein requirement than a dry cow.
  • Relative Forage Quality (RFQ): An index to compare quality. This combines ADF and NDF. The typical range is 50 to 250. The higher the number, the higher the quality.

Forage analysis can be overwhelming but preparing yourself with the tools to better understand the needs of your herd will prove to be the best course of action. A strong nutritional plan will positively impact profitability in both cow/calf and feeder operations. Work with a nutritionist to balance diets and supplement when needed. Beyond balancing diets, forage testing can help detect forage management issues that can be improved upon in the future. As always, Extension offers assistance interpreting results and can answer questions about forage testing.