Plant cell walls are a major constituent of feeding forages and can contribute to more than 50 % of the total dry matter (DM) weight of plants. In maize, a large proportion of the DM is in the ears, which contain mainly starch and therefore the contribution of cell walls in maize lower is relatively low, being 35 to 45 % of DM. The cell walls of plants are built up of cellulose, hemicellulose, lignin, pectin and protein. The content of cell walls is generally determined by washing plant materials with a neutral detergent, remaining only cellulose, hemicellulose and lignin. The protein in the NDF can be determined, but is often ignored.
Cellulose is a linear polymer of glucose. Hemicellulose is branched polymer of different sugars, such as glucose, arabinose, xylose, mannose, galactose, rhamnose etc. Lignin is a polymer of phenolic acids and is interwoven in the cell walls and is bound to the carbohydrates by ester or ether bonds.
The properties of cell walls, reflected in rate and extent of degradation in the rumen, are determined by many different things, such as: genotype of the plant, growing conditions (weather, water, fertilizer), maturity, chemical composition, physical characteristics and tissue distribution in the plant.
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Article made possible through the contribution of Lallemand Animal Nutrition.