Distiller s Grains with Solubles Did Not Influence Fecal Shedding of Escherichia coli O157:H7 in Experimentally Inoculated Feedlot Steers J.S. Drouillard Kansas State University, Manhattan, Kansas
Introduction E. coli O157:H7 is an important food-borne pathogen that causes disease in humans The gastrointestinal tract of cattle is a primary reservoir for E. coli O157:H7 Shedding of E. coli O157:H7 in cattle feces is highly erratic and unpredictable Diet may play an important role in colonization of the gut by E. coli O157:H7
Prevalence of E. coli O157 in Cattle Fed Finishing Diets 0 or 25% Wet Distiller s Grains (Jacob et al., 2008) P < 0.01 P > 0.2
Prevalence of E. coli O157 in Cattle Fed Finishing Diets with 0 or 25% Dried Distiller s Grains (Jacob et al, 2008) Effect of DDGS, P < 0.01
Concentrations of E. coli O157 in Feces of Experimentally Inoculated Cattle Fed Finishing Diets with 0 or 25% DDGS (Jacob et al., 2008) Effect of DDGS, P < 0.05
Concentrations of E. coli O157 in Feces of Experimentally Inoculated Cattle Fed Finishing Diets with 0 or 25% DDGS (Jacob et al., 2008) * * * * Effect of DDGS, P < 0.05
To determine if feeding dried distiller s grains with solubles affects shedding & persistence of E. coli O157:H7 in experimentally challenged cattle To determine if addition of dry-rolled corn to the diet can be used as a preharvest intervention strategy to reduce E. coli O157:H7 shedding
Holstein steers (n=39) Fecal samples were collected to determine prevalence of wild-type E. coli O157 A subset of 31 steers identified as negative for wild-type E. coli O157 were selected for the inoculation study
Stratified by initial body weight (213.5 20 kg) and assigned randomly, within strata, to 4 dietary treatments Treatments were arranged as a 2 x 2 factorial 0 or 25% dry-rolled corn (DRC) 0 or 25% dried distiller s grains with solubles (DDGS)
Diets, DM Basis a Ingredient, % 0% Dry-Rolled Corn 25% Dry-Rolled Corn 0% DDGS 25% DDGS 0% DDGS 25% DDGS Steam-flaked corn 82.1 58.2 56.8 33.1 Dry-rolled corn - - 25.5 25.3 Alfalfa hay 5.9 5.9 5.9 5.8 Dried distiller s grains - 25.4-25.3 Corn steep liquor 6.5 6.4 6.4 6.4 Limestone 1.5 1.6 1.5 1.6 Salt 0.3 0.3 0.3 0.3 Urea 1.2-1.2 - Premix 2.5 2.2 2.4 2.2 a Formulated to provide 300 mg/d monensin, 90 mg/d tylosin, 2200 IU/kg vitamin A, 0.30% salt, 0.70% calcium, 0.70% potassium, 60 mg/kg Zn, 60 mg/kg Mn, 10 mg/kg Cu, 0.6 mg/kg I, 0.25 mg/kg Se, and 0.1 mg/kg Co.
Methods Steers transitioned from roughage- to concentrate-based diets over a period of 3 wk Steers were relocated to individual pens in a biosafety level 2 facility Acclimated to the new environment for 2 d prior to initiating the challenge phase
Methods Steers orally dosed with a 5-strain mixture of Shiga-toxin producing Nal R E. coli O157 The inoculum for each calf contained approximately 3.2 x 10 9 CFU of Nal R E. coli O157 After inoculation, fecal samples collected from each steer 3 times/wk for 6 wk
Methods Nal R E. coli O157:H7 colonies were enumerated for each plate If colonies were not recovered by direct plating, they were subjected to secondary enrichment A colony from each plate was plated on blood agar and tested for indole production and O157 antigen latex agglutination
Methods At the termination of the study, all calves were euthanized and necropsied Contents from rumen, cecum, colon, and rectum were collected and concentrations of Nal R E. coli O157 were determined Rectal mucosa were swabbed and processed for detection of Nal R E. coli O157
Concentrations of Nal R E. coli O157 SEM = 0.29 No DDGS x DRC interaction, P> 0.2 Effect of sampling day, P < 0.01
Concentrations of Nal R E. coli O157 CFU/gram wet feces, Log10 6 5 4 3 2 1 0 SEM = 0.29 0% DRC 25% DRC 0 5 10 15 20 25 30 35 40 Day after oral dosing with Nal R E. Coli O157:H7 No effect of DRC, P > 0.5
Concentrations of Nal R E. coli O157 CFU/gram wet feces, Log10 6 5 4 3 2 1 0 SEM = 0.29 0% DDGS 25% DDGS 0 5 10 15 20 25 30 35 40 Day after oral dosing with NalR E. Coli O157:H7 No effect of DDGS, P > 0.7
Concentrations of Nal R E. coli O157:H7 in culture positive fecal samples 0% Dry-rolled Corn 0% DDGS 25% DDGS 25% Dry-rolled Corn 0% DDGS 25% DDGS SEM CFU, log10 2.48 2.77 2.66 2.78 0.27 No effect of DDGS, P > 0.4 No effect of DRC, P > 0.4 No DDGS x DRC interaction, P > 0.4
Concentrations at Necropsy of Nal R E. coli O157:H7 in GI Tract Contents CFU/gram of digesta, Log10 2.0 1.5 1.0 0.5 0.0 0% DRC, 0% DDGS 0% DRC, 25% DDGS 25% DRC, 0% DDGS 25% DRC, 25% DDGS Rumen Cecum Colon Rectum No effect of DDGS, P > 0.2 No effect of DRC, P > 0.2 No DDGS x DRC interaction, P> 0.2 SEM = 0.47
0% Dry-rolled Corn 25% Dry-rolled Corn 0% 25% 0% 25% DDGS DDGS DDGS DDGS SEM Rumen 37.5% 25.0% 14.3% 25.0% 1.08 Cecum 37.5% 37.5% 42.9% 25.0% 0.82 Colon 37.5% 37.5% 42.9% 50.0% 0.76 Rectum 62.5% 37.5% 28.6% 50.0% 0.84 RAMS 37.5% 25.0% 42.9% 62.5% 0.82 No interaction between distiller s grains and dry-rolled corn, P > 0.1 No effect of distiller s grains, P > 0.5 No effect of dry-rolled corn, P > 0.2
Summary Dried distiller s grains with solubles did not influence shedding rates of E. coli O157:H7 in experimentally challenged feedlot steers Addition of dry rolled corn did not impact shedding rates of E. coli O157:H7 in experimentally challenged feedlot cattle
Conclusions This study failed to corroborate earlier observations of an association between use of ethanol coproducts and increased prevalence of E. coli O157 Partial replacement of steam-flaked corn with dry- rolled corn does not appear to be effective as a preharvest intervention strategy to reduce prevalence of E. coli O157:H7 in feedlot cattle