The rumen microbial population is a complex ecosystem. Bacteria, protozoa, and fungi all play a part in degrading plant cell walls, which are a major substrate for energy and protein for the host animal. Rumen bacteria are considered to be the major degraders of forage fiber, but recent research has shown that rumen fungi are ubiquitous and are able to attack plant cell walls. Electron microscopy has been important in delineating the roles played by the various microbial types, including the fungi. The object of the present research was to assess the role of rumen fungi as degraders of particular tissues and to demonstrate that the presence of rumen fungi in the rumen can explain many of the unusual morphotypes associated with degradation of the more resistant tissues in forages.Rumen fungi were evaluated by inoculating tubes containing leaf blade sections of Cynodon dactyl on in a semi-synthetic, anaerobic medium with rumen fluid and incubating the tubes for 48 hours at 39°C. Some of the tubes contained streptomycin (2 mg/ml) and penicillin (2 x 10 units/ml) to inhibit bacteria.
