Demonstrating the different total mg and total mg/kg between two (hypothetical) farms with the same total kg of treated animals who are using AMs with different dose rates

FarmMedicineAM typeDose rate (mg/kg)Concentration (mg/ml)Total weight of treated animals (kg)AMU
Total mgTotal mg/kg
1Ceftiofur (Naxcel, Zoetis, UK)Third-generation cephalosporin6.620060 0003 96 0006.6
2Oxytetracycline (Terramycin LA, Zoetis, UK—long-acting dose)Tetracycline2020060 0001 200 00020
  • Farm 1 is using a third-generation cephalosporin (an HP-CIA), but, as the dose rate of cephalosporins is lower than that of tetracyclines, the total mg of medicine used on farm 1 is less than on farm 2, so both metrics appear to be lower for farm 1 than farm 2. The metrics ignore the fact that farm 1 is using an HP-CIA, which is arguably more important to reduce than just minimising total use when considering selection for antimicrobial resistance

  • AM, antimicrobial; AMU, antimicrobial use; HP-CIA, highest priority critically important antimicrobial.