应用差异光谱法建立绵羊采食复杂日粮干物质消化率模型的研究

研究旨在探讨利用放牧家畜“日粮—粪”差异光谱，建立干物质消化率模型的可行性。通过人工混合复杂日粮饲喂绵羊进行室内代谢试验，获得104份“日粮—粪”样品对，同时将相应的日粮和粪光谱做差获得104份差异光谱，将70份用于建模，34份用于检验。结合偏最小二乘法，利用差异光谱建立绵羊在采食成分较复杂时干物质消化率预测模型。最佳光谱范围为8 656～4 310 cm-1;光谱预处理方法以多元散射校正+一阶导数处理+Norris平滑(MSC+1st Deriv+Norris)处理的效果最好，最佳主因子数为7。经外部检验得到预测标准误差(RMSEP)为2.46%，相对标准误差(RPD)大于2.5，预测值与实际值的决定系数为0.833 9，说明所建近红外模型具有较好的预测效果。

Evaluation of Complex Diet Dry Matter Digestibility of Sheep Using Spectra Difference

The present study aimed to predict the dry matter digestibility (DMD) of animals fed complex diet using the spectra difference between diets and feces by near infrared reflectance spectroscopy (NIRS). Four indoor experiments were carried out with artificial mixed complex diets in the state field observatory stations located at Hebei province. The sheep were used as tested animals. One hundred and four parts of “diet-feces” were obtained and divided into a calibration sample set (70 samples) and a validation sample set (34 samples). The spectra difference between diets and feces, and the partial least square (PLS) were used to calibrate the models of DMD of sheep. The results indicated that the optimum range of spectrum was 8 656-4 310 cm-1. The optimum proceeding method was multivariate scattering correction + first derivative + Norris smoothing. The optimum number of factors was 7. The root mean square error of prediction (RMSEP) was 2.46%, and the RPD value of validation was above 2.5. The coefficient of correlation between the actual and predicted DMD using the NIRS was 0.8339, indicating that the NIRS could be used to evaluate dry matter digestibility of sheep fed complex diets.