There are bacteria called E. coli that can cause disease and death in young pigs, particularly nursery-age ones. Although antibiotics have been used to treat the disease, the bacteria have become resistant to most of them. New prevention or control procedures are needed for this disease. A promising new procedure involves the use of competitive exclusion (CE) bacterial cultures to reduce E. coli. The bacteria in the CE cultures were developed from the gut contents of a pig. These CE bacteria have been identified and are “good bacteria” that help in digestion, keep the intestinal tract healthy, and prevent disease-causing bacteria from gaining a foothold in the intestinal tract. When CE cultures are given to baby pigs, the intestinal tract becomes colonized by beneficial bacteria, which in turn, reduces the chance of E. coli infection. The purpose of the present study was to use field trials to evaluate the ability of a CE culture called RPCF to prevent or reduce E. coli disease in nursery-age pigs. These field trials were conducted in multiple states under commercial conditions and involved a total of 37,276 pigs. Six farms were identified as problem farms with a history of high mortality from E. coli. Newborn piglets were given an oral solution of RPCF while a similar number of piglets on the same farms served as untreated control pigs. Five out of the six farms experienced reduced mortality and medication costs in the RPCF-treated pigs compared to the untreated ones. There was an average cost saving of $24,563 per farm per year in the RPCF groups compared to the untreated groups. The results from these field trials indicate that RPCF is effective in reducing disease associated with E. coli and that RPCF might be a viable alternative to antibiotics for the future. Although RPCF is an experimental product, efforts are underway to pursue commercial development.