Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
The digestion of cellulose in the rumen requires the interaction of both cellulolytic and noncellulolytic bacteria, as well as protozoa.! Even when the energy source is entirely roughage material, the cellulase-producing bacteria comprise only about one-fourth of the total bacterial population. Major cellulolytic species include: Fuminococcus albus, Ruminococcus flavzfaciens, Bacteroides succinogenes, and Butyrivibrio fibrisolvens. Of these, Bacteroides succinogenes is the most active in digestion of cellulose, especially the more resistant forms.
Becht, Richard R.
"Effects of Isoacids on Ruminal Metabolism and Milk Production,"
Iowa State University Veterinarian: Vol. 49
, Article 3.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol49/iss1/3