Prediction of gas production kinetics of maize stover and ear by near infrared reflectance spectroscopy

This study was conducted to evaluate the potential of NIRS to predict gas production (GP) kinetics for maize ear and stover. Two approaches were applied to characterize GP kinetics: 1. describing GP profiles by fitting an exponential model and 2. by calculating GP for various incubation intervals. In the first approach, NIRS prediction equations could explain a high proportion of variability related to the fermentation rate (c), the asymptotic GP (A), and the lag phase (L) of ear samples in the calibration sub set (R²: 0.81-0.87), while for stover predictive ability was inferior. Validation showed satisfactory results only for the fermentation rate (R²: 0.81-0.88). In the second approach NIRS calibration was acceptable for GP in several incubation intervals, but validation showed satisfactory results for intervals 3-7, 7-12, and 7-16 h of stover samples only (R²>0.74). Further research is required to elucidate potential sources of error before obtaining robust NIRS equations.