Short communication: a novel system to estimate protein degradability in legume and grass hays

Previous research from our laboratory has demonstrated that near-infrared reflectance spectroscopy has utility in predicting rumen-undegradable protein (RUP) contents of legume and grass silages. This study was conducted to evaluate whether application of previous research techniques could yield a useful near-infrared reflectance spectroscopy RUP prediction system for legume and grass hays. Legume and grass hays (n = 106) were evaluated for RUP content by in situ techniques in four ruminally cannulated cows. In situ RUP for legume and grass hays averaged 25.9% CP and ranged from 14.6 to 45.5% CP, respectively. We developed a near-infrared reflectance spectroscopy RUP calibration equation for the legume and grass hay data set using in situ RUP contents as base data. This procedure resulted in an acceptable (R2 = 0.87, SE = 2.46% CP) near-infrared reflectance spectroscopy equation to predict RUP content of legume and grass hays. Data suggest that near-infrared spectroscopy predicts RUP contents of legume and grass hays with accuracies similar to legume and grass silages.