Concatenation of near- and mid-infrared spectra to improve calibrations for determining forage composition

The objective of this study was to determine the usefulness of combining near- and mid-infrared diffuse reflectance spectra to improve partial least squares calibrations. A set of 174 chlorite-treated feedstuffs were assayed chemically and spectroscopically for fiber, crude protein, lignin, digestibility, and lignin composition. All samples were scanned by diffuse reflectance in the near- and mid-infrared using a Fourier transform spectrometer equipped with a sample transport (to increase the amount of sample scanned) under various instrument configurations. Partial least squares analysis showed little or no improvement in calibration results by combining near- and mid-infrared spectra, although results using both regions together were at times better than those obtained using one of the two regions. In conclusion, results indicated that combining data from the near- and midinfrared spectral regions offers little or no advantage over the use of a single spectral range.