Extent of Cellulose and Hemicellulose Digestion in Various Forages by Pure Cultures of Rumen Bacteria

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Abstract
The ability of 9 pure strains of rumen bacteria to digest the cellulose and hemicellulose portions of an intact forage was investigated. Using a limiting level of substrate, the extent of digestion of these components was measured in varying maturity stages of both grasses and alfalfa. Bacteroides succinogenes strains were able to digest significantly greater amounts of cellulose from forages than were the other species. Two of the 4 strains of Ruminococcus flavefaciens used had a markedly reduced ability to digest cellulose from alfalfa. Of the 7 cellulolytic strains, only 3 were able to digest forage hemicelluloses. These 3 strains, all ruminococci, digested appreciable amounts of hemicellulose from bromegrass, but had a very limited ability to digest alfalfa hemicellulose. Opposite results were obtained with Bacteroides ruminicola. digested appreciable amounts of hemicellulose from both types of forage. Across all organisms and forages, the extent of both cellulose and hemicellulose digestion decreased with forage maturity. Studies on the possible symbiotic effect of combining 2 cultures in a single fermentation were conducted with 4 cellulolytic strains and 1 non-cellulolytic strain. All possible combinations of 2 were used, and a significant increase in the extent of cellulose digestion was consistently observed when the non-cellulolytic organism, B. ruminicola, was combined with any of the 4 cellulolytic strains.