Application of near infrared reflectance spectroscopy to protein analysis of grassland herbage samples

Near infrared reflectance spectroscopy (NIRS) was evaluated for the prediction of the protein content in samples of grassland herbage taken at different stages of maturity (flowering to fruiting stage) in ‘Dehesa’ zones of Central‐Western Spain. A Technicon Infra Alyzer model 500 scanning monochromator interfaced with a Hewlett‐Packard 1000 minicomputer was used for the study. Protein content was predicted with NIRS data treated as log I/R using six or seven wavelengths. Calibrations were evaluated by comparing Kjeldahl analyses with those predicted by NIRS. The prediction of protein was found to be acceptable, the standard error carying between 0.56 and 0.68% in a range of protein content from 6.76 to 13.98%