Use of NIRS to estimate the improvement in digestibility after ammonia treatment of cereal straws

Thirteen straw samples selected to show a broad range of organic matter digestibilities (32.3–46.1%) were analysed to measure the extent of improvement in digestibility after ammonia treatment and to find quick and useful predictors of the expected upgrading. provement in organic matter digestibility (OMD) ranged from 46.55–52.41%. No significant relationships were found between the increase in OMD after treatment and crude protein (CP), or neutral detergent fibre (NDF) of untreated straws. However significant relationships were found with acid detergent fibre (NDF) (r = 0.62; P < 0.05), acid detergent lignin (ADL) (r = 0.80; P < 0.01) and OMD (r = −0.94; P < 0.001). cond derivative NIR spectra after normalization for particle size by the detrended standard normal variate showed, a high negative correlation (r = −0.97, P < 0.001) with the improvement in digestibility. This result suggests that NIR spectra of untreated straws contains more information about the constituents and bonds responsible of the different responses to ammonia treatment, than OMD or indirect methods such as ADF or ADL.