[Evaluation of fermentation character of alfalfa silage through near infrared reflectance spectroscopy (NIRS)].

It is very important to evaluate the fermentation character of alfalfa silage using near infrared reflectance spectroscopy technology (NIRS) for animal production, including the content of NH3-N, lactic acid, acetic acid and butyric acid in silage. In order to evaluate the feasibility of using NIRS to analyze the formation character of alfalfa silage, the near infrared reflectance spectroscopy models were built for NH3-N, lactic acid, zcetic acid and butyric acid in this experiment. Partial least square regression (PLS), Fourier transform technology and sample preparation with liquid nitrogen technology were used to optimize the model. The analyzed samples were obtained with different cultivars, maturity, cuttings and ensiling method. The determination of cross validation was between 0.6024 and 0.9497. The standard errors of cross validation were between 5.59 x 10(-1) and 3.78 g x kg(-1) fresh weight. The validation samples were used to test the performance of the models. The correlation coefficients between the chemical value and the NIRS value were between 0.8826 and 0.9853, and the root mean square errors of prediction were between 5.71 x 10(-1) and 3.15 g x kg(-1) fresh weight. The results showed the NIRS could evaluate the fermentation of the fresh forage.