Nutritive evaluation of herbage from permanent meadows by near-infrared reflectance spectroscopy:: 1.: Prediction of chemical composition and in vitro digestibility

This study was implemented to evaluate the potential of near-infrared reflectance spectroscopy (NIRS) technology to estimate the chemical composition and in vitro digestibility of botanically complex herbage mixtures characterised, moreover, by a noteworthy variation among samples in the maturity of the forage plants. A total of 107 herbage samples harvested from permanent meadows located in the uplands of Leon (northwestern Spain) were analysed to determine their chemical composition. In addition, the in vitro digestibility of each herbage sample was measured by two different in vitro procedures using buffered rumen fluid. A Bran + Luebbe InfraAlyzer 500 spectrophotometer was used to obtain the near-infrared spectra corresponding to each herbage sample. Prediction equations developed for the estimation of the chemical components showed that NIRS technology could predict these parameters accurately, especially the crude protein and neutral detergent fibre contents (R-adj(2) > 0.95 in both cases). In vitro digestibility parameters could also be predicted with an acceptable degree of accuracy using NIRS technology, particularly the in vitro Tilley and Terry organic matter digestibility (R-adj(2) = 0.925, standard error of prediction (SEP) = 2.165% organic matter) and the in vitro dry matter true digestibility measured according to the Goering and Van Soest procedure (R-adj(2) = 0.891, SEP = 2.208% dry matter). (c) 2005 Society of Chemical Industry.