Analysis of Feed Barley by near Infrared Reflectance Technology

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Abstract
Rapid methods for predicting feed barley quality with near infrared (NIR) reflectance spectroscopy were investigated. Reference tests for true metabolisable energy (TME), in vitro digestibility, neutral-detergent fibre, protein and kernel plumpness in feed barley is time-consuming. Near infrared technology can save considerable time by testing all of the above simultaneously, but accurate calibration of the equipment is essential. Calibration requires accurate results from chemical or physical tests and wide variance in reference data. Our calibration data sets were selected from over 800 feed barley (hulless, two- and six-rowed) samples that were grown at various locations across the Canadian Prairies in 1990 or 1991. Calibrations for a NIRSystems 6500 scanning spectrophotometer, using both whole and ground kernels, were calculated using one of three basic mathematical treatments: log (1/ R) or the first or second derivative thereof. Partial Least Squares regression was applied to the best mathematical treatment and further calibrations were generated where applicable. We found correlations of 0.95 (TME), 0.98 ( in vitro digestibility), 0.90 (NDF), 0.97 (protein) and 0.91 (kernel plumpness). Standard errors of prediction were 0.21, 0.97, 0.65, 0.31 and 11.5, respectively.