U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

Effect of Direct-Fed Microbial Dosage on the Fecal Concentrations of Enterohemorrhagic Escherichia coli in Feedlot Cattle

Luedtke Brandon E., Bosilevac Joseph M., Harhay Dayna M., Arthur Terrance M.
Foodborne pathogens & disease 2016 v.13 no.4 pp. 190-195
Lactobacillus acidophilus, nutrition physiology, Propionibacterium freudenreichii, anus, beef, cattle, enterohemorrhagic Escherichia coli, feedlots, food safety, head, human diseases, inoculum, intestinal microorganisms, intestinal mucosa, probiotics, quantitative polymerase chain reaction, risk
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 10⁹ Propionibacterium freudenreichii and 10⁶ 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 10⁹ P. freudenreichii and 10⁹ 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.