Prediction error and repeatability of near infrared reflectance spectroscopy applied to faeces samples in order to predict voluntary intake and digestibility of forages by ruminants

The repeatability of FNIRS spectra and predictions assessed by repeated measurements of the same sample was satisfactory for all tested parameters. For OMD, DMVI, OMVI and the grass and clover proportion of the ingested forage, prediction repeatability was lower than, or similar to, the standard error of cross-validation (SECV) of the FNIRS calibration. The study showed that FNIRS could be a reliable method for predicting the OMD of ruminants, but the prediction of voluntary intake with acceptable error was less satisfactory because of uncertainties in the FNIRS calibration models.