Reduction of Pathogens in Feces and Lymph Nodes Collected from Beef Cattle Fed <i>Lactobacillus salivarius</i> (L28), <i>Lactobacillus acidophilus</i> (NP51) and <i>Propionibacterium freudenreichii</i> (NP28), Commercially Available Direct-Fed Microbials

The purpose of the study was to evaluate the prevalence and concentration of foodborne pathogens in the feces and peripheral lymph nodes (PLNs) of beef cattle when supplemented with direct-fed microbials (DFMs) in feedlots. Fecal samples were collected from the pen floors over a 5-month period at three different feedlots in a similar geographical location in Nebraska, where each feed yard represented a treatment group: (i.) control: no supplement, (ii.) Bovamine Defend: supplemented with NP51 and NP24 at a target dose of 9 log₁₀CFU/g/head/day, and (iii.) Probicon: supplemented with L28 at a target dose of 6 log₁₀CFU/g/head/day. Each fecal sample was tested for the prevalence of <i>E. coli</i> O157:H7 and <i>Salmonella</i>, and concentration of <i>E. coli</i> O157:H7, Enterobacteriaceae and <i>Clostridium perfringens</i>. Cattle were harvested and PLNs were collected on the harvest floor. Real-time <i>Salmonella</i> PCR assays were performed for each PLN sample to determine <i>Salmonella</i> presence. The cattle supplemented with both DFMs had reduced foodborne pathogens in fecal samples, but feces collected from the pens housing the cattle supplemented with Probicon consistently had significantly less <i>E. coli</i> O157:H7 and <i>Salmonella</i> prevalence as well as a lower <i>C. perfringens</i> concentration. While DFMs do not eliminate foodborne pathogens in fecal shedding and PLNs, the use of DFMs as a pre-harvest intervention allows for an effective way to target multiple pathogens reducing the public health risks and environmental dissemination from cattle.