2006 Annual Report 4d.Progress report. This report covers the research conducted under a trust agreement between ARS and National Cattlemen's Beef Association. Additional details of the research can be found in the report for the parent CRIS 5438-31430-003-00D Strategies to Optimize Carcass Yield and Meat Quality of Red Meat Animals. The objective of this project is to determine the effect of lower aging temperatures during refrigerated storage on the extent of postmortem proteolysis and tenderness of beef longissimus and gluteus medius and whether needle tenderization interacts with this effect. Six hundred cuts have been obtained and processed for this experiment and data collection is proceeding as planned.