201 - Forage Biodegradation: Advances in Ruminal Microbial Ecology

Abstract: The rumen microbial ecosystem provides ruminant animals a selective advantage, the ability to utilize forages, which allows ruminant animals to flourish around the world in a wide variety of environments. The ability of the microbial population to convert sunlight captured in forages to high quality meat, milk, and fiber has been recognized for many years. However, the rumen microbial population composition and degradative activity has remained a “black box” with only the most active (and most amenable to laboratory growth) cellulolytic and hemicellulolytic organisms being recognized and understood. The limitation of reliance upon growth of forage degrading organisms in a test tube in order to measure the catabolic activity, severely limited the development of knowledge of the microbial ecology of ruminal forage degradation. The past 15 years has seen the development and implementation of numerous Next-Generation Sequencing (NGS) approaches, which have greatly contributed to a better understanding of the microbial ecology of ruminants fed a variety of forages. NGS has provided new insights into changes in the microbial population of ruminants fed different diets, or undergoing dietary changes. The ability to take a “snapshot” of the composition of the ruminal microbial population has furthered our understanding of the impacts of forage maturity, forage type, and phytochemicals on the degradation and fermentation of forages. We now better understand the microbial pathways that are enriched by feeding of forages and are impacted by forage quality or composition, which can further our understanding of metabolomics of the rumen. As NGS data continues to accumulate on ruminants fed forage, our understanding of the ruminal microbial ecosystem will grow both deeper and broader, allowing us to build predictive models of rumen function during forage degradation and fermentation.