Longitudinal assessment of prevalence and incidence of Salmonella and Escherichia coli O157 resistance to antimicrobials in feedlot cattle sourced and finished in different regions of the U.S.

Authors: DORNBACH, COLTEN - Texas Tech University; HALES, KRISTIN - Texas Tech University; GUBBELS, ERIN - South Dakota State University; Wells, James - Jim; HOFFMAN, ASHLEY - Texas Tech University; HANRATTY, ASHLEE - Texas Tech University; LINE, DALTON - Texas Tech University; SMOCK, TAYLOR - Texas Tech University; MANAHAN, JEFF - Texas Tech University; MCDANIEL, ZACHARY - Texas Tech University; KOHL, KESLEY - Texas Tech University; Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; RUSCHE, WARREN - South Dakota State University; SMITH, ZACHARY - Texas Tech University; Broadway, Paul

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/17/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The objective was to investigate the influence of cattle origin and region of finishing on the prevalence of Salmonella, Escherichia coli O157:H7, and select antimicrobial resistance in E. coli populations. Yearling heifers (n = 190) were utilized in a 2 × 2 factorial arrangement. After determining fecal Salmonella prevalence, heifers were sorted into 1 of 4 treatments: heifers originating from SD and finished in SD (SD-SD); heifers originating from SD and finished in TX (SD-TX); heifers originating from TX and finished in SD (TX-SD); heifers originating from TX and finished in TX (TX-TX). Fecal, pen, and water scum line (WSL) samples were collected longitudinally throughout the study; hide and subiliac lymph node (SLN) samples were collected at study end. A treatment × time interaction was observed (P = 0.01) for fecal Salmonella prevalence, with prevalence being greatest for TX-TX and TX-SD heifers before transport. From d 14 through study end, prevalence was greatest for TX-TX and SD-TX heifers compared with SD-SD and TX-SD heifers. Salmonella prevalence on hides were greater (P = 0.01) for heifers finished in TX compared with SD. Salmonella prevalence in SLN tended (P = 0.06) to be greater in TX-TX and SD-TX heifers compared with TX-SD and SD-SD. Fecal E. coli O157:H7 prevalence had a treatment × time interaction (P = 0.04), with SD-TX prevalence being greater than TX-SD on d 56 and SD-SD and TX-TX being intermediate. A treatment × time interaction was observed for fecal trimethoprim-sulfamethoxazole-resistant and cefotaxime-resistant E. coli O157:H7 prevalence (P = 0.01). Overall, these data suggest region of finishing influences pathogenic bacterial shedding patterns, with the initial 14 d after feedlot arrival being critical for pathogen carriage.