RESUMO
The objective of this study was to determine the efficacy of the direct-fed microbial 10-G upon cattle growth performance, liver and lung health, carcass quality, and yield outcomes, as well as prevalence and enumeration of Salmonella in feces and lymph nodes. Fed beef heifers (Nâ =â 1,400; initial shrunk body weight [BW] 343.3â ±â 36.2 kg) were blocked by the day of arrival and randomly allocated to one of two treatments (0 [negative control, CON] or 2 g of a direct-fed microbial [10-G] that provided 1 billion CFUs per animal per day of Lactobacillus acidophilus, Enterococcus faecium, Pediococcus pentosaceus, L. brevis, and L. plantarum) with 10 pens per treatment. Recto-anal mucosal fecal samples (RAMs; nâ =â 477) and subiliac lymph nodes (SLNs; nâ =â 479) were collected longitudinally at harvest from 23 to 25 heifers per pen. Data were analyzed using mixed models; pen served as the experimental unit; block and harvest date were random effects. No differences were detected in dry matter intake (Pâ =â 0.78), final BW (Pâ =â 0.64), average daily gain (Pâ =â 0.51), gain to feed (Pâ =â 0.71), hot carcass weight (Pâ =â 0.54), dressed carcass yield (Pâ =â 0.52), 12th rib fat depth (Pâ =â 0.13), longissimus muscle area (Pâ =â 0.62), calculated empty body fat (Pâ =â 0.26), or marbling score (Pâ =â 0.82). Distributions of liver scores (Pâ ≥â 0.34), quality grades (Pâ ≥â 0.23), and yield grades (Pâ ≥â 0.11) were also not different between treatments. A tendency was detected for more normal lungs (Pâ =â 0.08; 10-Gâ =â 65.96%, CONâ =â 61.12%) and fewer inflated lungs at harvest for cattle fed 10-G (Pâ =â 0.10; 10-Gâ =â 0.29%, CONâ =â 1.16%); other lung outcomes did not differ (Pâ ≥â 0.54). Salmonella prevalence did not differ for RAM samples (Pâ =â 0.41; 10-Gâ =â 97.74%, CONâ =â 96.82%) or SLN (Pâ =â 0.22; 10-Gâ =â 17.92%, CONâ =â 13.66%). Salmonella concentration of RAM samples (Pâ =â 0.25; 10-Gâ =â 3.87 log CFU/g, CONâ =â 3.32 log CFU/g) or SLN (Pâ =â 0.37; 10-Gâ =â 1.46 log CFU/g, CONâ =â 1.14 log CFU/g) also did not differ between treatments at harvest. These results do not demonstrate any difference in live animal performance, carcass characteristics, or Salmonella carriage for heifers fed 10-G.