Prediction of lignin content in ruminant diets and faecal samples using rapid analytical techniques.

The measurement of lignin content in ruminant diet and fecal samples is important for digestibility studies, but it is typically time-consuming and costly. The work reported involves correlation of traditional wet chemistry data with those from three rapid instrumental techniques, Fourier transform infrared spectroscopy (FTIR), conventional thermogravimteric analysis (TGA), and high-resolution TGA (MaxRes TGA) to predict the lignin content of diets and feces from digestibility trials. Calibration and performance data indicate that the FTIR model is acceptable for screening, while the conventional and MaxRes TGA predictions are high accuracy for quantitative analysis. Cross validation and model performance data reveal that MaxRes TGA provides the best-performing predictive model. This work shows that MaxRes TGA can accurately predict lignin content in ruminant diet and fecal samples with distinct advantages over traditional wet chemistry: namely, the requirement of small sample size, ease of sample preparation, speed of analysis, and high sample throughput at considerably lower cost.