The objectives are to determine the effects of: (1) feedlot pen surface type (soil vs. pond ash), (2) animal stress-level on the prevalence and levels of E. coli O157:H7 and Salmonella spp. in feces and on hides of the penned cattle, and (3) the effects of feedlot pen surface type (soil vs. pond ash) on the prevalence, levels, and persistence of these pathogens in the manure collected from these two types of pen surfaces.
Findings: Pre-harvest strategies that reduce E. coli O157:H7 in cattle, thereby reducing the prevalence and numbers of this pathogen in the final meat product, are an important priority for the beef industry. Pond ash, a byproduct of coal-fired electricity generation that provides a hard surface when packed into layers, was examined as an alternative feedlot pen floor surface whose use may result in cleaner cattle and a reduction in E. coli O157 and Salmonella in cattle and the production environment. Large differences in E. coli O157 prevalence and levels in bovine feces, on hides, or in feedlot pen surface manure between clay soil and pond-ash surfaced pens were not observed, partially because pathogens declined over time in all pens. Furthermore, E. coli O157 populations survived similarly in manures deposited on these two different feedlot pen surfaces. No associations were detected between cattle heat stress risk factors or stress-level measurements and E. coli O157 prevalence or numbers in feces.