Because cultivation-basedapproaches to assess rumen microbiology assess only the minority of microbialgroups and can miss opportunities to assess important functions, molecular-basedapproaches have flourished in microbial ecology and have been adapted to therumen. Current approaches are described herein, specifically for a robust adaptationto nutrition studies or future opportunities. These included automated profilingtechniques, density gradient gel electrophoresis, and future adaption of microarrayor high-throughput sequencing technologies. Based on current knowledge, a moreholistic approach is needed to describe various functional groups of microbeswithin the context of how they influence, and are influenced by, the whole consortium(combination of microbial groups). Such a perspective is applied to issues relatedto increasing fiber digestibility when feeding concentrate or unsaturated fatsto high producing beef and dairy cattle. These same microbial populations shouldhelp to provide growth factors for fibrolytic bacteria while competing againstthe hyperammonia-producing bacteria such that there would be less need for excessiverumen-degraded protein as a safety factor. Moreover, these same dietary conditionsinfluence the processes of biohydrogenation and methanogenesis. After accountingfor population structures of bacteria, protozoa, methanogenic archaea, and evenfungi, efforts to integrate molecular-based rumen microbial ecology with dietaryconditions should allow us to better explain and therefore predict conditionsthat will improve feed efficiency and reduce environmental impact of ruminantproduction systems.
