Investigation of the relationship between manure processing method and presence of M. avium subsp. paratuberculosis and Salmonella spp. in recycled manure solids bedding on Midwest dairy farms

While many dairies use green (GRN) recycled manure solids (RMS) bedding, some first process slurry through an anaerobic digester (DIG), while others have adopted secondary (SEC) pro­cessing methods such as mechanical composters (COM), hot air dryers (DRY), or, more recently, infrared drying (IR), in an effort to lower mastitis pathogen counts in ready to use (RTU) solids. However, these processing methods could also poten­tially reduce levels of other important pathogens in RTU solids. Our objective was to investigate the relationship between use of DIG and other SEC processing methods on M. avium subsp. paratuberculosis (MAP) and Salmonella spp. (SAL) in RTU RMS on Midwest farms.