• Phytogenics (plant-based feed additives) have been suggested as suitable natural alternatives to help reduce the need for antimicrobials (Lillehoj et al., 2018).
  • This work is part of the Anpario’s 4R approach (Review, Reduce and Replace antimicrobials Responsibly) which helps manage gut health and support healthier livestock through the use of natural products.
  • Orego-Stim proved more effective than other commercially available phytogenics, producing a larger zone of inhibition against a specific resistant Escherichia coli (E. coli) strain.


  • The antibacterial effect of a product can be easily compared using a zone of inhibition test. This highlights the sensitivity of a known bacterial to multiple products.
  • The larger the zone of inhibition, the more effective the product is against the chosen bacteria.
  • Orego-Stim is a high quality, plant based eubiotic, containing 100% natural oregano essential oil.

An independent laboratory trial was carried out to compare the antibacterial effect of 5 phytogenic products on multi-drug resistant E. coli. Standardised Mueller Hinton plates were sourced pre-impregnated with the bacterium and the five treatments (Table 1) applied as per the laboratory standard protocol. Following incubation at room temperature for 24 hours each zone of inhibition on the plate was measured to determine antibacterial activity.

Table 1. The five commercially available products included in the study.      

Product Main Actives of the Product
1 Poppy alkaloids
2 Oregano oil
3 Oregano oil
4 Commercial blend of herbs including oregano
Orego-Stim 100% natural oregano essential oil



Figure 1. Zone of inhibition achieved with each product to determine antibacterial efficacy (mm).

Figure 2. Photograph of plate showing E. coli growth post incubation.

  • Orego-Stim showed an extensive 10mm zone of inhibition on the cultured agar plate. This was at least 100% better than any of the other products tested (Fig. 1).
  • The largest zone of inhibition recorded out of the five products tested was for Orego-Stim (Fig. 2).
  • Orego-Stim has been shown to be a highly effective, 100% natural product which can be effective in helping to inhibit resistance bacterial growth.