Abstract
Enterohemorrhagic Escherichia coli causes a potentially fatal disease in humans. Since human infections often occur following consumption of contaminated meat, strategies are sought to rid these pathogens from food-producing animals. E. coli, like most members of the family Enterobacteriaceae, possess respiratory nitrate reductase, an enzyme that coincidentally reduces chlorate to toxic chlorite. Consequently, a study was performed to assess the effect of intraruminal chlorate administration on E. coli in the gut of fed and fasted cattle, the latter having been reported to harbor increased concentrations of enteric pathogens. As hypothesized, E. coli concentrations were lower ( p <0.05) 10 and 24 h post chlorate administration, respectively, in rumen contents and feces of chlorate-treated cows than in untreated cows. Fasting had little effect on gut E. coli concentrations and did not effect the bactericidal effect of chlorate against E. coli. Chlorate treatment had little or no effect on fermentation efficiency, as evidenced by pH, volatile fatty acid production and concentration of total culturable anaerobes, and had no observable adverse effects on any of the cows. These results suggest that chlorate may be useful in the pre-harvest control of E. coli.