Measurement of chemical composition in wet whole maize silage by visible and near infrared reflectance spectroscopy

Abstract

Visible (Vis) and near infrared reflectance (NIR) spectroscopy were used to predict dry matter (DM), acid and neutral detergent fibre (ADFom and aNDFom), ash, crude protein (CP) and pH in wet whole maize (WWM) silage samples. Samples were analysed by reference methods and spectra collected using a NIR spectrophotometer in reflectance (400–2500 nm). Predictive equations were developed using modified partial least squares (MPLS) with full cross validation using raw spectra or second derivative. Two scatter corrections were also used, namely standard normal variate and detrend (SNVD) and multiplicative scatter correction (MSC). Coefficient of determination in calibration R cal 2 and standard error of cross validation (SECV) were 0.91 (SECV: 6.5 g kg −1 DM) for CP, 0.85 (SECV: 27.4 g kg −1) for DM using SNVD, and 0.86 (SECV: 22.1 g kg −1 DM) for ADFom using raw spectra. Poor correlations between the reference methods and NIR were found for aNDFom, ash, OMD and pH. It was concluded that NIR spectroscopy might be a suitable method to predict DM, CP and ADFom on WWM silage samples with minimal sample preparation.