Publication Date

1985

Location

Kyoto Japan

Description

Lignin concentration and chemical composition, associated phenolic monomers, and arabinose branching of the xylose core of hemicellulose are all thought to affect the rate and/or extent of digestion. This study was conducted to investigate the influence of maturity on rate of cell wall ( CW) digestion of stems from two legume species and on CW constituents in legume and grass stems. The rate of CW digestion was determined by fermenting samples in rumen fluid for various periods. Structural carbohydrate composition was determined in ethanol-insoluble residues and phenylpropanoid components were determined in CW after alkali treatment and nitrobenzene oxidation. Rate of CW digestion was similar for alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) and for immature and mature stems. Mature stems of both legume and grass species had a high xylose/arabinose ratio and a low vanillin/ syringaldehyde ratio. Mature grass stems also had a high p­coumaric/ferulic acid ratio. Birdsfoot trefoil (Lotus corniculatus L.) stems were low in syringaldehyde. Chemical composition of lignin from alfalfa and red clover stems seems to be somewhat similar to that from stems of the grasses. Ferulic and p-coumaric acid probably are important in limiting the digestion of grass species. The chemical changes that occur in alfalfa and red clover stems with maturity seem to have little effect on rate of digestion.

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Digestibility and Chemical Composition of Cell Walls from Grass and Legume Stems

Kyoto Japan

Lignin concentration and chemical composition, associated phenolic monomers, and arabinose branching of the xylose core of hemicellulose are all thought to affect the rate and/or extent of digestion. This study was conducted to investigate the influence of maturity on rate of cell wall ( CW) digestion of stems from two legume species and on CW constituents in legume and grass stems. The rate of CW digestion was determined by fermenting samples in rumen fluid for various periods. Structural carbohydrate composition was determined in ethanol-insoluble residues and phenylpropanoid components were determined in CW after alkali treatment and nitrobenzene oxidation. Rate of CW digestion was similar for alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) and for immature and mature stems. Mature stems of both legume and grass species had a high xylose/arabinose ratio and a low vanillin/ syringaldehyde ratio. Mature grass stems also had a high p­coumaric/ferulic acid ratio. Birdsfoot trefoil (Lotus corniculatus L.) stems were low in syringaldehyde. Chemical composition of lignin from alfalfa and red clover stems seems to be somewhat similar to that from stems of the grasses. Ferulic and p-coumaric acid probably are important in limiting the digestion of grass species. The chemical changes that occur in alfalfa and red clover stems with maturity seem to have little effect on rate of digestion.