Direct-Fed Microbials in Diets of Market Pigs Did Not Impact Salmonella Levels, Shiga Toxin-Producing Escherichia coli, Growth Performance, and Carcass Characteristics

• Salmonella prevalence in market pigs was very low. • E. coli O111 prevalence in market pigs was very low. • E. coli O157:H7 was not detected in market pigs. • Probiotics did not impact Salmonella or Shiga toxin-producing E. coli prevalence in market pigs. • Probiotics did not impact market pig performance metrics or any carcass traits. Salmonella enterica and Shiga toxin-producing Escherichia coli (STEC) have been associated with the gastrointestinal tracts of growing-finishing swine. Identification of pre-harvest pathogen mitigations is imperative. The probiotics BIOPLUS 2B and Probicon L28 were evaluated as direct-fed microbials to 1) reduce Salmonella and STEC in the lymph nodes and feces of commercial growing-finishing pigs, and 2) improve growth performance and carcass characteristics. Market pigs (n=650) were fed a standard corn-soybean meal finishing diet according to the following treatments: Probicon L28 at 1.0×10 6 CFU/head/day (Probicon); BIOPLUS® 2B at 3.0×10 9 CFU/head/day (BIOPLUS 2B); and a control (Control). Fecal samples, boot covers, and chew ropes (tied to pen) were collected upon arrival (baseline), 6 wk post-placement, and prior to loadout (13 wk post-placement). Superficial inguinal lymph nodes (SILNs) were collected at the abattoir. Salmonella and STEC occurrences were determined for all samples. Pen (∼21-day intervals) and individual weights were used to assess growth performance. Carcasses were evaluated by hot carcass weight, loin depth, backfat, and percentage lean. Salmonella prevalence in group 1 and group 2 market hogs was 0.7% and 2.8% in feces, and 0.8% and 0% in SILNs, respectively. STEC O111 was infrequently detected (n=5 samples), and E. coli O157:H7 was not detected. The impacts of BIOPLUS® 2B and Probicon L28 on the prevalences of STEC genes ( stx and eae ) and STEC serogroups O26, O121, O45, O103, and O145) in feces, boot covers, chew ropes, and SILNs of market pigs were not different ( P >0.05). Overall average daily gain, average daily feed intake, gain:feed ratio, and carcass traits did not differ ( P >0.10) between treatments.