Microbial attack on lignocellulose in the rumen

The microbial population of the rumen consists of many types and species of anaerobic and facultatively anaerobic microorganisms, often at high population densities, living in symbiosis with the animal. The animal is unable to synthesize enzymes capable of digesting the major structural components of plant cell walls (fiber) and relies on the rumen microbes to ferment this material with the generation of volatile fatty acids and microbial cells that the animal can utilize. The crude fiber fraction of ruminant forages consists mainly of cellulose, hemicellulose, and lignin.