Publication Date
1989
Description
The nutritive value of forage for ruminants is limited by the digestibility of the complex polysaccharides cellulose and hemicellulose by rumen microbes. In grasses, the polysaccharide fraction of the cell wall is composed largely of polymers of neutral sugars and to a lesser extent uronic acids. Cellulose is a high molecular weight linear polymer of B-1 ➔ 4) linked Dgluco-pyranose units. Hemicellulose is a complex mixture of linear and branched-chain heteropolymers containing xylose, arabmose, mannose, galactose, glucose, and uronic acids (Van Soest, 1982). Lignification of the cell wall is a primary factor limiting the digestion of cell wall polysaccharides. Close physical association of lignin with the polysaccharides within the cell wall matrix and the existence of covalent bonds between lignin and the polysaccharide fraction limits the accessibility of the polysaccharides as substrate for the hydrolytic enzymes secreted by rumen microbes (Jung and Fahey, 1983). Brown midrib (bmr) mutants of sorghum [Sorghum bicolor (L.) Moench] have been identified which contain lower concentrations of lignin than do their normal counterparts (Fritz et al., 1981). In addition to quantitative differences, lignin compo sition ot: bmr lignin is also qualitatively different. In general, bmr _ hgnms contain less alkali-extractable p-coumaric acid and more vanillin than normal lignin (Cherney et al., 1986, Fritz et al., 1989) Because of these characteristics, brm mutants provide a unique opportunity for studying the effects of lignification on ruminal fiber digestion. The objective of this experiment was to study the in situ digestion of the neutral sugar component of cell walls of a normal and bmr mutant of sorghum x sudangrass.
Citation
Moore, K J.; Fritz, J O.; and Jaster, E H., "In situ Degradation of Cell Wall Neutral Sugars of Normal and Brown Midrib Sorghum x Sudangrass Hybrids" (2025). IGC Proceedings (1989-2023). 87.
https://uknowledge.uky.edu/igc/1989/session7/87
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
In situ Degradation of Cell Wall Neutral Sugars of Normal and Brown Midrib Sorghum x Sudangrass Hybrids
The nutritive value of forage for ruminants is limited by the digestibility of the complex polysaccharides cellulose and hemicellulose by rumen microbes. In grasses, the polysaccharide fraction of the cell wall is composed largely of polymers of neutral sugars and to a lesser extent uronic acids. Cellulose is a high molecular weight linear polymer of B-1 ➔ 4) linked Dgluco-pyranose units. Hemicellulose is a complex mixture of linear and branched-chain heteropolymers containing xylose, arabmose, mannose, galactose, glucose, and uronic acids (Van Soest, 1982). Lignification of the cell wall is a primary factor limiting the digestion of cell wall polysaccharides. Close physical association of lignin with the polysaccharides within the cell wall matrix and the existence of covalent bonds between lignin and the polysaccharide fraction limits the accessibility of the polysaccharides as substrate for the hydrolytic enzymes secreted by rumen microbes (Jung and Fahey, 1983). Brown midrib (bmr) mutants of sorghum [Sorghum bicolor (L.) Moench] have been identified which contain lower concentrations of lignin than do their normal counterparts (Fritz et al., 1981). In addition to quantitative differences, lignin compo sition ot: bmr lignin is also qualitatively different. In general, bmr _ hgnms contain less alkali-extractable p-coumaric acid and more vanillin than normal lignin (Cherney et al., 1986, Fritz et al., 1989) Because of these characteristics, brm mutants provide a unique opportunity for studying the effects of lignification on ruminal fiber digestion. The objective of this experiment was to study the in situ digestion of the neutral sugar component of cell walls of a normal and bmr mutant of sorghum x sudangrass.
