Predicting fecal composition of grazing beef cattle by near infrared spectroscopy

The study evaluated the feasibility of near infrared spectroscopy (NIRS) to predict the feces composition of grazing beef cattle. The experiment was conducted in the long-term grazing experimental platform of the National Field Observation and Research Station of the Hulun Buir Grassland Ecosystem in the Chinese Academy of Agricultural Sciences. The feces samples of 72 grazing beef cattle were collected using the whole fecal collection method and analyzed using the partial least squares (PLS) method, combined with different spectral processing and software analyses. A calibration model for near infrared analysis of fecal components was established and evaluated by the predicting parameters of C, N, OM, ADF and NDF. The coefficient of determination (R²) of C, N, OM, ADF and NDF was 0.90, 0.96, 0.91, 0.23, and 0.49, and the relative analysis error (RPD) was 2.45, 2.81, 1.94, 1.00, and 1.09, respectively. The model could be used to predict the fecal content of C and N in grazing beef cattle, but the prediction accuracy needs further improvement. For OM, ADF and NDF need further study and analysis.