Anpario awarded UK patent for Orego-Stim, the composition of which reduces antimicrobial resistance in calves


Anpario, the independent manufacturer of natural, sustainable feed additives for health, nutrition and biosecurity, has successfully been granted a UK patent for their leading phytogenic product Orego-Stim. The composition of which is effective in reducing antimicrobial resistance*.

The patent grant follows a combined and successful research programme with the University of Reading. The research demonstrated that the proportion of E. coli bacteria resistant to a fourth-generation cephalosporin antibiotic, can be significantly reduced by adding the natural oregano essential oil composition to calf diets, according to research undertaken at the University of Reading in the UK.


Antimicrobial resistance is one of the greatest threats globally to human health and has been predicted to be responsible for 10 million deaths a year by 2050 if not acted upon.


University researchers Dr Partha Ray and Dr Caroline Rymer, undertook the trial to determine the effect of supplementing Anpario’s Orego-Stim Liquid (a source of 100 percent natural oregano essential oil), in waste milk fed to dairy calves, on the population of antimicrobial resistant bacteria in their faeces. This resistance can occur when calves are fed waste milk or colostrum containing antibiotic residues.

Waste milk occurs on farms when cows have been treated for a disease, such as mastitis, with antibiotics. The milk from these cows cannot be sold for human consumption and, as it contains valuable nutrients, is often fed to pre-weaned calves.

In the trial, two-day old Holstein male calves were offered either waste milk with Orego-Stim Liquid added for the first ten days or a control diet of the same waste milk source without the addition of Orego-Stim Liquid. After the initial ten days, all calves were fed the same ration of untreated waste milk and concentrates until weaning at 8 weeks of age.

In the faeces of calves fed waste milk with no Orego-Stim, 44.1 percent of E. coli present were resistant to the cephalosporin antibiotic (cefquinome). However, in calves fed waste milk supplemented with Orego-Stim Liquid until day ten, this was significantly reduced, with only 12.6 percent of total E. coli being resistant to cefquinome.

Dr Partha Ray commented “Oregano essential oil supplementation not only reduced the abundance of cefquinome-resistant E. coli but also delayed the emergence of resistance to cefquinome”.

David Wilde, Anpario’s global innovation manager and ruminant specialist summarised the importance of the research. “Waste milk is a valuable resource on all dairy farms and disposing of it in slurry lagoons only transfers the AMR issue elsewhere. This important work shows that it may be possible to support gut and animal health when using natural products and allow the continued use of this vital calf feed.”

For further information, see

 * Patent grant GB2585132B.