Near infrared reflectance spectroscopy for predicting intake of digestible organic matter by cattle

The near infrared reflectance spectra of 15 forages and the first and second derivatives of those spectra were examined for variations that would relate to measures of forage quality and animal performance. Strong relationships between second derivative values and protein, NDF, ADF, and digestible DM were found at wavelengths reported previously as well as at other wavelengths. Error mean squares for simple regressions were similar to those previously reported for multiple wavelength regressions. The more important measures of forage quality, digestible organic matter intake and average daily body weight gain, were each highly correlated with second derivative values at 1696 and 2298 nm (r greater than /.91/). Second derivatives at 1696 and 2298 nm were also correlated (r greater than /.95/) with ADF and protein, respectively. The evidence suggests a biological basis for the estimation of digestible organic matter intake from near infrared reflectance spectroscopy spectra.