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

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 × 106 CFU/head/day (Probicon); BIOPLUS® 2B at 3.0 × 109 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.