Conclusions
The populations of uncultured bacteria can be as great
as those of major cultured bacteria. These uncultured
bacteria are also ubiquitous in the rumen. Uncultured
bacteria may play as an important role as some of the
cultured bacteria, if not more. Comparative dynamic
studies of uncultured bacteria in response to dietary
treatments might help further reveal their ecological
niche and roles in the rumen. Isolation and
characterization of as-yet uncultured bacteria in the
rumen would need to be attempted to define their functions
and contribution to rumen functions.