Microscopical aspects of rumen microbial colonization and degradation of forage tissues

Abstract

Observation by microscopy of the different tissues of forage plants shows they are made of cells whose cell walls differ from one tissue to another in thickness, lignification, etc. The disappearance of the different tissues in the rumen occurs in a particular order: the phloem and the parenchyma disappear first while the xylem vessels remain extensively undegraded. Degradation of leaf tissues is more rapid than that of the stem.

A comparative study of normal and bm3 maize has shown that the lignified walls of the mutant line, which is more digestible, are partially degraded in the rumen. The degradation of the tissues during plant maturation is reduced by lignification of the cell walls. Alkali treatment of cereal straws allows the degradation of some cell walls that are undegradable in untreated plants. The microorganisms involved in plant cell wall degradation can be observed by microscopy. The adhesion of bacteria to cell walls, the swallowing of plant fragments by protozoa and the particular process by which anaerobic fungi colonize lignified tissues are described.