Location: Food and Feed Safety Research
Title: Influence of wet distiller's grains on prevalence of E. coli O157:H7 and Salmonella in feedlot cattle and antimicrobial susceptibility of generic E. coli isolates Authors
Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2009
Publication Date: May 15, 2010
Citation: Edrington, T.S., MacDonald, J.C., Farrow, R.L., Callaway, T.R., Anderson, R.C., Nisbet, D.J. 2010. Influence of wet distiller's grains on prevalence of E. coli O157:H7 and Salmonella in feedlot cattle and antimicrobial susceptibility of generic E. coli isolates. Foodborne Pathogens and Disease. 7(5):605-608. Interpretive Summary: Distiller’s grains are a by-product from the production of ethanol and are used as a feed by the cattle industry. Recent expansion of the ethanol industry has increased the amount of distiller’s grains being fed to cattle. This change in diet could influence the bacterial diversity in the gastro-intestinal tract of the animal and increase the prevalence of important bacteria such as E. coli O157:H7 and Salmonella. Fecal samples were collected from feedlot cattle fed distiller’s grains for varying lengths of time and cultured for the above bacteria. No differences were observed in the concentrations or prevalence of E. coli O157:H7 or Salmonella in this study.
Technical Abstract: The current research examined the inclusion of 20% wet distiller’s grains (WDG) fed with steam-flaked (SFC) or dry-rolled (DRC) corn in diets fed to feedlot cattle on fecal prevalence of E. coli O157:H7 and Salmonella. Crossbred beef heifers (n = 272; average initial body weight (BW) = 354 kg) were blocked by BW and pen size and randomly assigned to treatment. Fecal samples from freshly voided fecal pats were collected from each pen on the day cattle shipped for slaughter (237 fecal samples: 72, 125, and 40 from cattle and 132, 160, and 181 days on feed, respectively). Fecal samples were cultured quantitatively and qualitatively for the above pathogens. Populations of E. coli O157:H7 and Salmonella were generally low with very few samples containing quantifiable populations. Similarly, following enrichment, few samples were E. coli O157:H7 positive in any collection with no treatment differences (P > 0.10). More samples were Salmonella positive during the first collection, with an increased (P < 0.05) prevalence observed in the SFC and DRC treatments compared to DRC+WDG treatment. No other treatment differences were observed for Salmonella. Generic E. coli (GEC) isolates (18 per treatment; first collection) were examined for antimicrobial susceptibility, and most were susceptible to all of the antibiotics examined. Most of the resistance was observed in the SFC and DRC treatments, and only one isolate in each of the two WDG treatments demonstrated resistance (one antibiotic each, streptomycin, and tetracycline). All multi-drug resistance (2 - 4 antibiotics) was observed in isolates cultured from the DRC and SFC treatments. Results of the current research found no significant effect of WDG on fecal prevalence of E. coli O157:H7 and only modest decreases in Salmonella prevalence. No apparent effect on antimicrobial susceptibility of GEC isolates was observed.