Abstract
Background: The number and diversity of uncultured ruminal bacterial and archaeal species revealed by 16S rRNA
gene (rrs) sequences greatly exceeds that of cultured bacteria and archaea. However, the significance of uncultured
microbes remains undetermined. The objective of this study was to assess the numeric importance of select
uncultured bacteria and cultured bacteria and the impact of diets and microenvironments within cow rumen in a
comparative manner