Investigation of Feedlot-level Use of a Direct-fed Microbial on Fecal Shedding of E. coli O157:H7

• Published in: Journal of food protection 2024-11, Vol.87 (11), p.100370, Article 100370
• Main Authors: Edache, David O., Baruch, Joaquin, Kreikemeier, Wanda, Nagaraja, Tiruvoor G., Renter, David R., Smolensky, Dmitriy, Cernicchiaro, Natalia
• Format: Article
• Language: English
• Subjects: Animal Feed; Animals; Bacterial Shedding; Cattle; Colony Count, Microbial; Direct fed microbials; E. coli O157:H7; Escherichia coli Infections - epidemiology; Escherichia coli Infections - veterinary; Escherichia coli O157; Fecal prevalence; Feces - microbiology; Feedlot cattle; Lactobacillus - isolation & purification; Nebraska; Preharvest; Prevalence; Propionibacterium
• ISSN: 0362-028X; 1944-9097; 1944-9097
• DOI: 10.1016/j.jfp.2024.100370

•The association between DFM status and E. coli O157 prevalence varied by month.•Body weight and weather were associated with fecal prevalence of E. coli O157:H7.•Highest prevalence estimates were observed between late July and mid-August.•Mid-summer DFM administration was associated with lower E. coli O157 prevalence. Our objectives were to determine whether the feedlot-level use of a direct-fed microbial (DFM; Lactobacillus animalis LA51 and Propionibacterium freudenreichii PF24; Bovamine Defend®, 2 × 109 CFU/g) was associated with fecal prevalence and concentration of E. coli O157:H7, and determine pen- and feedlot-level risk factors associated with fecal E. coli O157:H7 prevalence in cattle pens from commercial feedlot operations. Twenty commercial feedlots in Nebraska, ten that included DFM (DFM) and ten that did not (no-DFM), were sampled during the summer of 2017. In each sampling month, 22 pen-floor fecal samples were collected from three pens in each feedlot. Samples were subjected to cultural and molecular procedures for the detection of E. coli O157:H7 (immunomagnetic separation, plating on selective media, followed by PCR confirmation) and spiral plating for quantification. A total of 1,320 samples from 180 pens of finishing cattle belonging to 20 feedlots, which were sampled three times throughout a 12-week period, were processed and tested. Across all feedlots and sampling months, the mean within-pen prevalence was 13.5% (95% CI = 2.6–47.4%). The association between DFM status and the within-pen prevalence of E. coli O157:H7 depended significantly (p