Faecal near infrared spectroscopy (NIRS) as a tool to asses rabbit's feed digestibility

Near-infrared reflectance spectroscopy (NIRS) technology has been successfully used to monitor nutrition in ruminants through diet and/or faeces, but few studies have used this technology to predict rabbit diet's digestibility. The aim of this study was to evaluate the feasibility of faecal NIRS to predict chemical composition of faeces and nutrient digestibility of fed diets from rabbit in vivo digestibility trials. Also, the use of faecal spectra to directly predict chemical composition of fed diets was evaluated. A total of 80 dried and ground faeces samples from a digestibility trial were scanned in rectangular quartz cups in a FOSS-NIRSystems 6500 SY-II scanning monochromator. Faecal Modified Partial Least Squares calibration equations showed good predictive values for dry matter, organic matter, crude protein, crude fibre and ash not only in faeces (r2 values from 0.73 to 0.95) but also in fed diets (r2 values from 0.92 to 0.95). Additionally, faecal equations were suitable to predict digestibility coefficients of the diets (r2 values from 0.65 to 0.86). This work supports the viability of faecal near infrared spectroscopy as a fast and reliable analytical method, which could allow important savings in rabbit digestibility trials.