Lignin-carbohydrate complexes in forages: structure and consequences in the ruminal degradation of cell-wall carbohydrates

Lignin-carbohydrate complexes (LCCs) are recognised as key structures in forage degradability. Apart from ester bonds involving phenolic acids, which seem to play a major role in grasses, little is known about the other types of linkages that must exist but have proved difficult to demonstrate. The chemical nature of possible LCC linkages is presented and the various mechanisms through which LCCs in the cell-wall architecture may interfere with carbohydrate utilisation by rumen microorganisms are discussed.