title: Effect of Direct-Fed Microbial Dosage on the Fecal Concentrations of Enterohemorrhagic Escherichia coli in Feedlot Cattle.
abstract: Contamination of beef products by Shiga toxin-producing Escherichia coli is a concern for food safety with a particular subset, the enterohemorrhagic E. coli (EHEC), being the most relevant to human disease. To mitigate food safety risks, preharvest intervention strategies have been implemented with the aim to reduce EHEC in cattle. One class of interventions that has been widely used in feedlots is direct-fed microbials (DFMs), which can contain various dosing rates of probiotic bacteria. Here we compare the use of two different doses of a commercially available DFM on total EHEC load in a commercial feedlot setting. The DFMs used were the standard 10(9) Propionibacterium freudenreichii and 10(6) Lactobacillus acidophilus colony forming units (CFUs)/head/day dose of Bovamine(®) (Nutrition Physiology Company, Guymon, OK) and the higher dose, Bovamine Defend™ (Nutrition Physiology Company), which is dosed at 10(9) P. freudenreichii and 10(9) Lactobacillus acidophilus CFUs/head/day. To analyze the total EHEC fecal concentration, 2200 head of cattle were assigned a DFM feed regimen lasting approximately 5 months. At harvest, 480 head of cattle were sampled using rectoanal mucosal swabs. A quantitative polymerase chain reaction assay targeting ecf1 was used to enumerate the total EHEC fecal concentration for 240 head fed the low-dose DFM and 240 head fed the high-dose DFM. No significant difference (p > 0.05) in the fecal concentration of total EHEC was observed between the two doses. This suggests that using an increased dosage provides no additional reduction in the total EHEC fecal concentration of feedlot cattle compared to the standard dosage.
authors.affiliation: 1 U.S. Department of Agriculture * , Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.|2 Department of Biology, University of Nebraska at Kearney , Kearney, Nebraska.
authors.forename: Brandon E
authors.initials: BE
authors.lastname: Luedtke
authors.affiliation: 1 U.S. Department of Agriculture * , Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Bosilevac
authors.affiliation: 1 U.S. Department of Agriculture * , Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: Dayna M
authors.initials: DM
authors.lastname: Harhay
authors.affiliation: 1 U.S. Department of Agriculture * , Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: Terrance M
authors.initials: TM
authors.lastname: Arthur
mesh_terms: D001003:Anal Canal / Q000382:microbiology; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000517:prevention & control*; D015169:Colony Count, Microbial / Q000662:veterinary; D004269:DNA, Bacterial / Q000302:isolation & purification / Q000378:metabolism; D054324:Enterohemorrhagic Escherichia coli / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D005243:Feces / Q000382:microbiology*; D007413:Intestinal Mucosa / Q000382:microbiology; D007779:Lactobacillus acidophilus / Q000254:growth & development; D008297:Male; D058889:Molecular Typing / Q000662:veterinary; D009516:New Mexico; D009919:Orchiectomy / Q000662:veterinary; D019936:Probiotics / Q000008:administration & dosage* / Q000627:therapeutic use; D000070002:Propionibacterium freudenreichii / Q000254:growth & development; D012007:Rectum / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial