Year of Publication

2021

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Animal and Food Sciences

First Advisor

Dr. Rachel R. Schendel

Second Advisor

Dr. William Boatright

Abstract

Arabinoxylan (AX) is a major structural polysaccharide found in the cell walls of monocots such as cereal grains and pasture grasses. The variety of AX structural components and substitution patterns contribute to AX structural diversity between different monocot species as well as plant tissues.

The rumen is the first digestion site of masticated food material in cattle and provides 70% of energy to host through fermentation of forage. There are many species of pasture grasses that act as a forage source. Differences in AX structure found in these pasture grasses may impact rumen microbial fermentation. Understanding the AX structure of different pasture grasses can elucidate how different AX structures can impact rumen microbial fermentation.

The objectives of this research were to develop a high-performance anion-exchange chromatography (HPAEC-PAD) method to rapidly quantify AX oligosaccharides (or AXOS) released via endoxylanase digestion and characterize the AX structure in four cool-season pasture grasses from central KY (timothy, perennial rye, tall fescue, and bluegrass). Quantification of AXOS enabled the comparison of AX structural profiles between grass materials.

An HPAEC-PAD method was developed and validated for xylanase-released AXOS using analytical parameters concentration range (CR), limit of detection (LOD), limit of quantification (LOQ), retention time (tR HPAEC), and relative response factor (RRF). Perennial rye tended to have greater amounts of AXOS compared to the other pasture grasses. 3X was released by endoxylanase in greatest amounts compared to other AXOS (significant difference varies). In addition, the cell wall monosaccharide and ester-linked hydroxycinnamic acid (HCA) contents were profiled in each cool-season pasture grass.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.032

Funding Information

This study was supported by the Sustainable Forage-Based Production for the Mid-South Transition Zone, ARS Project # 5042-21000-002-00D from the United States Department of Agriculture in 2018.

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