Microlocalization and distribution of digestionresistant aromatic lignin and cellulosic compounds in feeds at cellular and subcellular levels: A novel approach

Abstract

The objective of this study was to micro-localize the distribution of digestion-resistant aromatic lignin and cellulosic compounds in feeds at cellular and subcellular levels using advanced synchrotron-powered FTIR microspectroscopy (SFTIRM) as a novel approach. The SFTIRM is a newly emerging and nondestructive analytical technique and can reveal molecular chemistry (structural-chemical make-up) of biological samples at highly spatial resolutions (3-10 µm) without destruction of the feed internal structures. The exampled feeds used for this pilot study were maize (cv. Pioneer) and barley (cv. Harrington). The results show that with SFTIRM, the images of the aromatic lignin and cellulosic compounds could be generated to be able to show the distribution and intensity across the feeds tissues. The digestion-resistant aromatic lignin compound only presented in the pericarp region and no lignin has been found in seed coat, aleurone layer and endosperm. The cellulosic compounds presented most in the pericarp region, less in the seed coat, aleurone layer, and endosperm. The agglomerative hierarchical cluster analysis (AHCA) and principal component analysis (PCA) showed the distinct differences of the chemical make-up between the two feeds (maize vs barley) and between the different structures (pericarp vs aleurone) within a feed. Even in the same structural regions (such as aleurone layer, and endosperm), the structural make-up were different between the maize and barley. This may explain why digestive behaviours are different between the barley and maize. The implication of this study is that with extremely bright synchrotron light, we can localize and characterize internal feed digestion-resistant compounds in a chemical sense withJournal of Animal and Feed Sciences, 16, 2007, 505-525 506 LIGNIN AND CELLULOSE IN FEEDS AT CELLULAR LEVEL cellular dimensions. With respect to human and animal nutrition, it is possible to relate digestive function and nutrient utilization to the specifi c chemical make-up of intrinsic structures of feeds. It is believed that with the advanced synchrotron technology, it will make a signifi cant step and an important contribution to feed molecular structural research.