Grelet C, Fernández Pierna J A, Dardenne P, Baeten V, Dehareng F
Walloon Agricultural Research Center, Valorisation of Agricultural Products Department, 24 Chaussée de Namur, 5030 Gembloux, Belgium.
Walloon Agricultural Research Center, Valorisation of Agricultural Products Department, 24 Chaussée de Namur, 5030 Gembloux, Belgium.
J Dairy Sci. 2015 Apr;98(4):2150-60. doi: 10.3168/jds.2014-8764. Epub 2015 Feb 11.
The goal of this study was to find a procedure to standardize dairy milk mid-infrared spectra from different Fourier transform mid-infrared spectrophotometers (different brands or models) inside a European dairy network to create new farm-management indicators (e.g., fertility, health, feed, environmental impact) based on milk infrared spectra. This step is necessary to create common spectral databases, allowing the building of statistical tools, to be used by all instruments of the network. The method used was piecewise direct standardization (PDS), which matches slave-instrument spectra on master-instrument spectra. To evaluate the possibility of using common equations on different instruments, the PDS method was tested on a set of milk samples measured on each machine, and an equation predicting fat content of milk is applied on all. Regressions were performed between master and slaves fat predictions, before and after PDS. Bias and root mean square error between predictions were decreased after PDS, respectively, from 0.3781 to 0.0000 and from 0.4609 to 0.0156 (g of fat/100mL of milk). The stability over time of these results was confirmed by an application of the coefficients created by PDS 1 mo later on the slave spectra. These preliminary results showed that the PDS method permits a reduction of the inherent spectral variability between instruments, allowing the merging of Fourier transform mid-infrared milk spectra from different instruments into a common database, the creation of new types of dairy farm management indicators, and the use of these common calibrations for all Fourier transform mid-infrared instruments of the European dairy network.
本研究的目标是找到一种程序，对欧洲乳制品网络内不同傅里叶变换中红外分光光度计（不同品牌或型号）测得的牛奶中红外光谱进行标准化，以便基于牛奶红外光谱创建新的农场管理指标（如繁殖力、健康状况、饲料、环境影响）。这一步骤对于创建通用光谱数据库至关重要，该数据库可用于构建统计工具，供网络中的所有仪器使用。所采用的方法是分段直接标准化（PDS），即将从属仪器的光谱与主仪器的光谱进行匹配。为了评估在不同仪器上使用通用方程的可能性，对在每台仪器上测量的一组牛奶样品进行了PDS方法测试，并将一个预测牛奶脂肪含量的方程应用于所有样品。在PDS前后，分别对主仪器和从属仪器的脂肪预测值进行回归分析。PDS后，预测值之间的偏差和均方根误差分别从0.3781降至0.0000，从0.4609降至0.0156（克脂肪/100毫升牛奶）。通过在1个月后将PDS创建的系数应用于从属光谱，证实了这些结果随时间的稳定性。这些初步结果表明，PDS方法能够减少仪器之间固有的光谱变异性，从而允许将不同仪器测得的傅里叶变换中红外牛奶光谱合并到一个通用数据库中，创建新型的奶牛场管理指标，并将这些通用校准用于欧洲乳制品网络的所有傅里叶变换中红外仪器。
