[Calibration Transfer of Near Infrared Spectrometric Models for Crude Protein of Protein Feed Materials].

The near infrared spectrometric quantitative model of protein feed and its sharing in different instruments can greatly improve the utilization efficiency of the model and meet the needs of rapid development of feed industry. Considering the issue of applicability of near infrared spectrometric models for crude protein of protein feed materials, calibration transfer was explored among three types of instruments using spectral subtraction correction, direct standardization and piecewise directs standardization methods for the first time. Four kinds of protein feed raw materials were involved in the present study, corn protein powder, rapeseed meal, fish meal and distillers dried grains with soluble. The experimental instruments included MATRIX-I Fourier transform near infrared instrument (master instrument), Spectrum 400 Fourier transform near infrared instrument (slave 1 instrument), and SupNIR-2750 grating near infrared instrument (slave 2 instrument). Results showed that the spectral data difference for all the samples between the master and slave 2 instrument was relatively small, and the difference between the master and slave 1 instrument, and slave 1 and slave 2 instrument were relatively large. All the root mean square error of prediction and bias values after calibration transfer were lower than the values before calibration transfer, except that no improvement was found for the prediction of corn protein powder of slave 2 instrument corrected by piecewise direct standardization method. The relative prediction deviation (RPD) of corn protein powder, rapeseed meal and distillers dried grains with soluble transferred by all three methods were higher than 3, which indicated good predictions, while the RPD of fish meal were all higher than 2.5, which indicated relative good predictions. All three techniques used in the study were effective in the correction of the difference between different instruments for protein feed materials. This study is of important practical significance for the application of near infrared spectrometric models for crude protein of protein feed materials.