New/emerging Measurements for Forage Quality

A nationally accepted standard hay test for alfalfa hay has included measurement of Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), Dry Matter (DM) and Crude Protein (CP). Total Digestible Nutrients (TDN) has typically been calculated directly from a fiber measurement, usually ADF. However, this is likely to change. While there are a range of points of view on forage testing, it is likely that forage testing will evolve towards greater use of NDF, estimates of NDF digestibility (NDFD), and use of summative equations to predict feeding value. ADF, developed as a preparative step for lignin, will be de-emphasized. Greater inclusion of ash measurements, protein fractions are likely. Techniques such as the gas evolution method may provide important added dimensions to forage measurements. Summative equations, which incorporate several measurements, may provide improved prediction of quality, especially for forages of similar ADF, but with different known performance. Adoption of these analyses will be limited by uncertainty about consistency of measurement and marketing considerations. While markets prefer single measurements of forage quality, the ability to incorporate multiple measurements is critical for improved prediction of quality from forages, since forage quality is by definition multidimensional.