Effects of feeding 10-G direct-fed microbial on feedlot performance, carcass characteristics, and prevalence of <i>Salmonella</i> in subiliac lymph nodes of feedlot steers

Yearling crossbred beef steers [n = 6,400; initial body weight (BW) 358 kg] were used to investigate the efficacy of a direct-fed microbial upon animal growTh performance, carcass characteristics, and prevalence of <i>Salmonella</i> in subiliac lymph nodes after a feeding duration of 182 d. Steers were allocated to 1 of 32 pens [n = 200/pen] within 16 total blocks, and assigned to 1 of 2 dietary treatments; no probiotic (<b>CON</b>) or 2 g*steer^-1*d^-1 of <i>Lactobacillus acidophilus</i>, <i>Enterococcus faecium</i>, <i>Pediococcus pentosaceus</i>, <i>Lactobacillus brevis</i> and <i>Lactobacillus plantarum</i> providing a total of 1 billion CFU (<b>10-G</b>). At harvest, subiliac lymph nodes were randomly obtained from 40 animals from each pen for blocks 1 through 10. Data were analyzed as a randomized complete block design, and pen served as the experimental unit. No differences (<i>P</i> ≥ 0.26) were observed between treatments for DMI, final BW, average daily gain, or feed efficiency. When evaluating carcass characteristics, there were no differences (<i>P</i> ≥ 0.15) for hot carcass weight or liver abscess prevalence. However, dressed carcass yield differed (<i>P</i> = 0.02) between treatments (CON = 64.74%, 10-G = 64.52%). No differences (<i>P</i> ≥ 0.12) were observed for marbling score, longissimus muscle area, 12^th rib s.c. fat depth, or USDA quality grade outcomes. Lower frequency (<i>P</i> < 0.01; CON = 36.95%, 10-G = 23.60%) of <i>Salmonella</i> positive subiliac lymph nodes was observed for cattle supplemented dietary 10-G, whereas concentration of <i>Salmonella</i> quantifiable samples did not differ (<i>P</i> = 0.23) between treatments (CON = 0.84 Log₁₀CFU/g, 10-G = 0.63 Log₁₀CFU/g). In conclusion, the supplementation of 10-G direct fed microbial did not influence live or carcass performance within this trial; however, prevalence of <i>Salmonella</i> positive subiliac lymph nodes was reduced.