Beef Species Symposium: nutrient requirements of the beef female in extensive grazing systems--considerations for revising the Beef NRC.

The B eef Species Symposium titled “Nutrient Requirements o f the B eef Female in Extensive Grazing Systems— Considerations for Revising the B eef NRC” was held at the Joint Annual Meeting o f the American Dairy Science Association and American Society o f Animal Science in Indianapolis, IN, July 8 to 11, 2013. The committee for this symposium was composed o f a subset o f members o f the W1012 Improving ruminant use o f forages in sustainable production systems for the western U.S. multistate project. They included Allison M. Meyer (University o f Wyoming), Dan B. Faulkner (University o f Arizona), Eric J. Scholljegerdes (New Mexico State University), Jim E. Sprinkle (University o f Arizona), Sergio A. Soto-Navarro (New Mexico State University), Richard C. Waterman (USDA-ARS Fort Keogh Livestock and Range Research Laboratory), Joel S. Caton (North Dakota State University), Mark K. Petersen (USDA-ARS Fort Keogh Livestock and Range Research Laboratory), Chad J. Mueller (Oregon State University), Kenneth C. Olson (South Dakota State University), and Jack C. Whittier (Colorado State University). The purpose o f the symposium was to pres­ ent current information on the specific characteristics o f grazing environments in the western United States as they relate to the nutrient requirement predictions o f the beef female. These grazing environments are dynamic, with changes occurring within season, from year to year, and across soil types, topography, and elevation. Such grazing circumstances are also highly variable with di­ verse plant communities and level and timing o f precipi­ tation patterns. Beef cows on western ranges have dem­ onstrated their ability to adapt to such variation through