Evaluation of various NIR instruments for estimating grain quality for livestock

Abstract

A large national research project in Australia over the past seven years has focused on improving the quality of grains for feeding to livestock. A major expectation of the grain and livestock industries from this project is the adoption of rapid and objective analytical tests for relevant quality criteria of grains, preferably at the point of delivery. NIR spectroscopy obviously has a key role, and calibrations have been derived, or attempted, for 52 different chemical and physical properties, several in vitro or in sacco tests, and in vivo digestibility or energy content for ruminants [1 - 3], pigs and poultry. Final calibrations were developed using over 100 grains, either whole or ground, which were scanned on laboratory-based grating monochromators, namely Foss-NIRSystems models 6500 or 5000 instruments. However, the industry has requested that the appropriate NIR spectroscopy testing procedures be made available on simpler, cheaper and as such, often older, spectrometers. This presents a real challenge for calibration transfer, given the differences in optical configuration, spectral range, sample presentation and software packages among the instrument types. Some instruments also target specific applications and constituents. Due to the nature of many of the tests of interest in this project, it was a difficult task to make direct and fair comparisons between NIR spectrometers in the market-place. The purpose of this study was to compare the accuracy of some NIR spectrometers for estimation of selected indicators of feed grain quality, using whole grain samples.