FTIR	Fourier-transform infrared
CP	crude protein
NDF	neutral detergent fibre
ADF	acid detergent fibre
PLSR	partial least squares regression
RFR	random forest regression
BP	back-propagation
BC	baseline correction
CARS	competitive adaptive reweighted sampling
SG1D	first-derivative Savitzky–Golay preprocessing
SG	Savitzky–Golay preprocessing
MSC	multiplicative scatter correction
airPLS	adaptive iteratively reweighted penalised least squares
SPA	successive projections algorithm
PCA	principal component analysis
RPD	residual predictive deviation
RMSE	root mean square error
R2	coefficient of determination