The Use of near Infrared Spectroscopy for the Analysis of Fresh Grass Silage

Abstract

The feasibility of using near infrared reflectance and near infrared transmission spectroscopy to evaluate the proximate composition and the content in fermentation end-products of fresh silage was investigated. In this study, the silage fermentation characteristics were predicted both by NIR reflectance (NIRSystems 6500 with a coarse sample cell) and by NIR transmittance (Tecator Infratec 1255). The silage was measured immediately on opening the silo with no sample preparation. The analysis of silage in its fresh state prevents volatilisation of fermentation end-products. The best results were obtained in the reflectance mode for all the constituents under investigation, using the full wavelength range. The best R2 values for pH, ammonia-nitrogen, lactic and acetic acids for validation samples were 0.90, 0.93, 0.86 and 0.85, respectively. The corresponding standard error values were 0.23 and 1.07 (% of total nitrogen), 8.35 and 1.65 (g kg−1 dry matter). It is concluded that silage fermentation characteristics can be predicted by NIR analysis on the silage in its fresh state. In this manner, the volatilisation of fermentation end-products is prevented.