2004 Annual Report 4.What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a specific cooperative agreement between ARS and the Department of Microbiology at Cornell University. Additional details of research can be found in the report for the parent project 1907-31000-005-00D "Alternative Mechanisms for Improving Ruminal Fermentation". This project began in May 2004. The objective is to isolate and identify ruminal bacteria responsible for ruminal lysine degradation and to study the effect of the feed additive, monensin, and bacteriocins on lysine degradation. Lysine is often an amino acid that limits milk production, but bacteria responsible for wasteful ruminal lysine degradation have not yet been identified. Mixed ruminal bacteria will be enriched with lysine in vitro, and bacteria capable of utilizing lysine will be isolated, characterized physiologically, tested for their susceptibility to monensin and bacteriocins, and identified via 16 S rDNA sequencing. Cattle will be supplemented with lysine to see if these same bacteria increase in vitro.