Applications of hierarchical cluster analysis (CLA) and principal component analysis (PCA) in feed structure and feed molecular chemistry research, using synchrotron-based Fourier transform infrared (FTIR) microspectroscopy.

Synchrotron technology based Fourier transform infrared microspectroscopy (S-FTIR) is a recently emerging bioanalytical microprobe capable of exploring the molecular chemistry within microstructures of feed tissues at a cellular or subcellular level. To date there has been very little application of hierarchical cluster analysis (CLA) and principal component analysis (PCA) to the study of feed inherent microstructures and feed molecular chemistry between feeds and/or between different structures within a feed, in relation to feed quality and nutrient availability using S-FTIR. In this paper, multivariate statistical methods--CLA and PCA--were used to analyze synchrotron-based FTIR individual spectra obtained from feed inherent microstructures within intact tissues by using the S-FTIR as a novel approach. The S-FTIR spectral data of three feed inherent structures (strucutre 1, feed pericarp; structure 2, feed aleurone; structure 3, feed endosperm) and different varieties of feeds within cellular dimensions were collected at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL), U.S. Department of Energy (NSLS-BNL, New York). Both PCA and CLA methods gave satisfactory analytical results and are conclusive in showing that they can discriminate and classify inherent structures and molecular chemistry between and among the feed tissues. They also can be used to identify whether differences exist between the varieties. These statistical analyses place synchrotron-based FTIR microspectroscopy at the forefront of those new potential techniques that could be used in rapid, nondestructive, and noninvasive screening of feed intrinsic microstructures and feed molecular chemistry in relation to the quality and nutritive value of feeds.