2005 Annual Report 4d.Progress report. This report serves to document research conducted under Specific Cooperative Agreement #58-5434-3-307 between ARS and Montana State University. Additional details of research can be found in the report for the parent project 5434-31000-014-00D Develop Beef Cattle Better Suited for Sustainable Production. Reduced shedding of E. coli O157:H7 would be useful in controlling contamination of meat. Seventy one cows were vaccinated approximately 30 days before parturition with an experimental vaccine and then co-mingled with 66 non-vaccinated control cows. Serum and fecal samples were collected from cows at vaccination and approximately 14 d postpartum. Serum and fecal samples were collected from calves at approximately 14 and 60 d postpartum. Vaccination of cows markedly increased antibody titers against E. coli O157:H7 in both cows and calves. However, differences between treatments in shedding of E. coli O157:H7 were not detected in calves at approximately 60 d of age as less than 5% of calves were shedding. Results indicate efficacy of vaccinating the gestating cow against E. coli O157:H7 in increasing antibody titers of both cow and suckling calf. A project has been initiated to determine changes muscle satellite cell proliferation and fusion in response to compounds in growth promoting implants.