Potential use of visible and near infrared reflectance spectroscopy for the estimation of nitrogen fractions in forages harvested from permanent meadows

7 pages, 3 tables.One-hundred and ninety-two herbage samples from permanent meadows located in the mountains of Leon (NW Spain) were analyzed for total nitrogen (total N), nitrogen in trichloroacetic acid precipitated matter (TCAN), borate-phosphate buffer insoluble nitrogen (BPBN), neutral-detergent insoluble nitrogen (NDIN) and acid-detergent insoluble nitrogen (ADIN). These data were used to calculate the partition of nitrogen fractions proposed by the Cornell Net Carbohydrate and Protein System (CNCPS): A (total. N - TCAN), B, (TCAN - BPBN), B-2 (BPBN - NDIN), B-3 (NDIN - ADIN) and C (ADIN). Near-infrared reflectance spectroscopy (NIRS) technology accurately predicted total N, TCAN and NDIN, as judged by coefficient of determination (R-2) and ratio performance deviation (RPD) values greater than 0.90 and 2.5, respectively. The rest of the insoluble N fractions (BPBN and ADIN) were predicted with less accuracy by NIRS. Estimations of CNCPS N fractions (A, B-1, B-2, B-3 and C) using visible-NIR spectra of forage samples did not allow accurate predictions (R-2 < 0.90; RPD < 2.5).This work was supported by the Universidad de León (Project ULE-2002-24) and by Excelentísima Diputación Provincial de León (Project Efecto de la época de corte y de la fertilización mineral sobre el valor nutritivo de forrajes de la montaña de León).Peer reviewe