Handheld NIRS for forage evaluation

Abstract

Handheld near infrared reflectance (NIR) instruments are now available for non-scientist operators for on-farm evaluation of forages. There are a variety of instruments with different detector technologies and greatly different NIR scanning ranges. However, there is little public data or independent evaluation of their relative effectiveness in the field. Our objective was to evaluate several hand-held NIR instruments for precision and accuracy of currently available calibrations for dry matter (DM) compared to a state-of-the-art electronic moisture meter, and to evaluate forage nutritive value calibrations available on one instrument. The AuroraNir, NIR4, and SCiO handheld NIR instruments were evaluated, along with the HST-1 electronic impedance moisture probe. Over 600 haylage, corn silage and total mixed ration samples were collected in 2019 and 2020 from 19 dairy farms in NY and WI. After scanning, two subsamples of each sample were dried to determine oven DM. Samples from three of the 19 farms were measured 10 times each, with remixing between measurements, to evaluate precision. The Aurora and NIR4 instruments, with a similar NIR scanning range, were similar in precision for estimating oven DM, while the SCiO and HST-1 instruments were less precise. Using currently available calibrations, accuracy of DM estimations was in the order of AuroraNIR > NIR4 ≫ SCiO > HST-1, although current calibrations were not sufficiently robust for a range of mixed haylage, corn silage and TMR samples from NY and WI. Calibrations for the AuroraNir did not produce consistently accurate results for nutritive value determinations, particularly when dealing with mixed species haylage.