The Effect of Stage of Maturity and Lignification on the Digestion of Cellulose in Forage Plants by Rumen Microorganisms In Vitro

Abstract

The in vitro digestibilties of cellulose within various whole plant materials and cellulose-containing fractions (isolated cellulose and holocellulose) were determined by an in vitro technique. Plant materials at different stages of maturity were investigated: first, second and third stages of orchard grass, alfalfa and timothy. Lignin content was correlated with the digestion of cellulose within the whole plant materials. The results of the investigation showed that separating cellulose from lignin greatly improved its digestibility in vitro. However, cellulose in holocellulose, which also contains hemicellulose, was similar in digestibility to isolated cellulose. This would indicate that lignin but not hemicellulose has an inhibitory effect upon cellulose digestion. Maturity of plant material has an effect upon cellulose digestion—the young plant cellulose being the more digestible. The effect of maturity diminished greatly when the cellulose was isolated from the plant, either as holocellulose or as cellulose. A negative relationship existed between lignin content and the in vitro cellulose digestion in the whole plant materials.