ISSUE FOCUS 52 FEED & ADDITIVE MAGAZINE March 2026 The gold standard for testing procedures is wet chemistry methodologies. More recently, near-infrared spectroscopy (NIR) methods have been improved and become mainstream for routine analyses. One advantage of using NIR methods is the lower cost. One concern with NIR methods is the inability to accurately assess mineral content. Quality laboratories will indicate what feeds are appropriate for NIR testing as accurate calibrations have not been generated. Most forage samples will have good calibration criteria to assess nutrient content other than minerals. FEED ANALYSIS TERMINOLOGY A major hurdle in the use of feed testing and its application is the complex terminology associated with all the parameters determined. Here is a summary of the key parameters on a forage test that should be considered in evaluating the forage quality. Moisture – Dry Matter. We talk about feeds on an “as fed” and “dry matter” basis relative to a feeding program. When you send a sample to the lab, the feed contains both moisture and dry matter. Dry matter is where all the nutrients are found. The lab will weigh the sample, dry it, then reweigh it to determine the moisture loss, leaving only the dry matter. We want to compare feeds on a dry matter basis to compare “apples to apples” as the moisture content varies. For hay the moisture should be 15% or less. As the moisture increases, the risk of promoting mold growth increases. Mold growth increases the risk for heat generation and spontaneous combustion of hay bales. Moisture content of feeds to be ensiled is critical to successful fermentation. Large round hay bales often have enough moisture to allow mold growth, leading to the degeneration of the forage quality in the center of the bale. This process may become excessive, allowing for the growth of Listeria or the organism causing botulism. Crude Protein (CP). Forage protein content is a reasonable marker of forage quality, with more immature plants having greater protein content compared to mature plants (Table 1). Feed protein content (termed Crude Protein [CP]) is determined by Hay Type and Maturity Stage Alfalfa Pre-bloom Early bloom Mid bloom Late bloom Grass Prehead Early head Head Post-head CP % DM > 19 17-19 13-16 < 13 > 18 13-18 8-12 < 8 ADF % DM < 31 30-35 36-41 > 41 < 33 34-38 39-41 > 41 NDF % DM < 40 40-46 46-51 > 51 < 55 55-60 61-65 > 65 ME Mcal/lb 1.03 - 1.13 0.98 - 1.02 0.92 - 0.97 < 0.90 0.98 - 1.07 0.85 - 0.91 0.75 - 0.84 < 0.75 TDN % DM 63 - 66 60 - 62 56 - 59 < 55 60 - 65 52 - 56 46 - 51 < 46 Table 1. Typical test value of alfalfa and grass forages harvested at various stages of plant maturity (all values on dry matter basis). Abbreviations: CP = crude protein; ADF = acid detergent fiber; NDF = neutral detergent fiber; ME = metabolizable energy; TDN = total digestible nutrients.
RkJQdWJsaXNoZXIy MTUxNjkxNQ==