Comparative analysis of compact and benchtop near-infrared spectrometers for forage nutritional trait measurements

We compared near-infrared (NIR) partial least squares models of a compact and a benchtop spectrometer to measure six nutritional traits of Brachiaria forages, including in-vitro dry matter digestibility (IVDMD), crude protein (CP), crude fiber (CF), acid detergent fiber (ADF), neutral detergent fiber (NDF), and lignin (LG). The relative prediction errors (RMSE/mean) for both instruments varied between 1.5% (for NDF) and 13% (for CP). Additionally, we obtained multivariate figures of merit and used a robust randomization t-test to comprehensively compare the two instruments. Our results show that, despite its lower analytical sensitivity, the compact instrument performs sufficiently well compared to the benchtop instrument and can be used for routine measurement of all six forage nutritional traits. The small performance difference between the two spectrometers can primarily be attributed to the narrower spectral range measured by the compact instrument.