Prediction of Ruminal Protein Degradability of Forages Using near Infrared Reflectance Spectroscopy

AbstractRuminal protein degradability is an important trait affecting forage quality, but in situ procedures used to characterize protein degradability are costly and time consuming. Our objectives were to compare an in situ procedure with a ficin protease extraction procedure for estimating ruminal protein degradability of forages and to determine whether near infrared reflectance spectroscopy (NIRS) can provide similar estimates of protein degradability compared to either method. Ruminal protein degradability of five cool‐season perennial grasses and alfalfa was determined using the ficin protease procedure. Ficin‐extracted crude protein (CP) represents that portion of CP that is solubilized in the extraction procedure; it accounted for 66% (in grasses) to 93% [in alfalfa (Medicago sativa L.)] of the variation of in situ degradable crude protein. NIRS accurately predicted in situ and ficin degradability on a dry matter basis, but not on a CP basis. We concluded that the ficin procedure could substitute for the in situ determination of ruminal degradable protein and that NIRS could be used to predict protein degradability determined by either method.