近红外光谱快速分析青贮饲料pH值和发酵产物

采用近红外光谱技术,结合偏最小二乘回归法,研究了142个不同种类的秸秆青贮饲料样品的pH值和发酵产物(乳酸、乙酸、丙酸、丁酸和氨态氮),建立了干燥粉碎和新鲜样品的近红外漫反射光谱定量分析模型以及浸提液样品的近红外透射光谱定量分析模型。研究发现,pH值的近红外漫反射光谱和透射光谱的分析效果均较好,校正模型决定系数R2和验证集样品预测值与化学值的相关关系决定系数r2都大于0.80,并且干燥粉碎、新鲜和浸提液样品的RPD值分别为3.44、2.50和2.27;3种状态样品的乳酸、乙酸、丁酸和氨态氮的定量分析模型精度需进一步提高;R2在0.64~0.85之间;RPD值在1.38~1.93之间;丙酸含量的测定结果较差。方差分析显示,3种状态样品的测定结果之间均无显著性差异(P>0.05)。

Rapid Prediction of pH Value and Fermentation Products in Silage by Near Infrared Spectroscopy

Near infrared spectroscopy calibrations of pH value and fermentation products(lactic acid, acetic acid, propionic acid, butyric acid and ammonia) in 142 straw silage samples were studied by the means of partial least-squares(PLS) regression. The calibrations for dried and fresh samples of silage were analyzed by near infrared diffuse reflectance spectroscopy(NIDRS), and the calibrations for silage soak and extract samples were analyzed by near infrared transmittance spectroscopy(NITS). Good calibrations of NIDRS and NITS were found for pH value, the corelation coefficients of calibration(R2) and correlation coefficients of validation(r2) were all greater than 0.80, and the ratio of performance to standard deviation(RPD) value for dried, fresh and silage soak and extract samples were 3.44, 2.50 and 2.27, respectively. The calibrations of lactic acid, acetic acid, butyric acid and ammonia need to be improved, and the coefficient R2 and RPD values were among 0.64-0.85 and 1.3-2.0, respectively. It was hard for NIDRS and NITS to analyze propionic acid, and the coefficient R2 and r2 for dried, fresh and silage soak and extract samples were all lower than 0.45. The results of dried, fresh and silage soak and extract samples were not evident(P>0.05).