New research from the University of Reading in the U.K. suggests that the levels of Escherichia coli bacteria resistant to a fourth-generation cephalosporin antibiotic may be significantly reduced by adding an oregano essential oil to calf diets, according to an announcement from Anpario, which sponsored the research.
University of Reading researchers Partha Ray and Caroline Rymer undertook a trial to determine the effect of supplementing a source of 100% natural oregano essential oil (Anpario’s Orego-Stim Liquid) in waste milk fed to dairy calves on the population of antimicrobial resistant bacteria in their feces, Anpario said.
Holstein male calves were offered either waste milk treated with oregano essential oil for 10 days or a control diet of the same waste milk source without the addition of the essential oil, according to the announcement. After the initial 10 days, all calves were fed the same ration of untreated waste milk and concentrates until weaning.
According to the study results, supplementing oregano essential oil may offer a potential solution to help reduce the presence of antimicrobial-resistant bacteria in dairy calves.
In the feces of calves fed waste milk with no essential oil, 44.1% of E. coli present were resistant to the antibiotic cephalosporin (cefquinome). However, in calves fed waste milk supplemented with the oregano until day 10, this was significantly reduced to only 12.6% of total E. coli being resistant to cefquinome, Anpario said.
“Oregano essential oil supplementation not only reduced the abundance of cefquinome-resistant E. coli but also delayed the emergence of resistance to cefquinome,” said Ray, a lecturer in dairy animal science at Reading University. “We are conducting further studies to understand the mechanism underlying the effect of [oregano essential oil] feeding on antimicrobial resistance in the gut of young cattle. Improving our understanding of the mechanism is the only way we can refine the practice of feeding the essential oil-based supplement to make it more sustainable.”
Rymer, associate professor of animal science at Reading University, added, “Feeding supplements which have antimicrobial activity may themselves encourage the development of antimicrobial resistance. It was, therefore, very pleasing that there was no evidence that feeding [oregano essential oil] increased the resistance of E. coli to any of the antibiotic classes tested. It was even more promising that resistance to the critically important cefquinome was reduced.”