Use of antimicrobials for food animals in New Zealand: updated estimates to identify a baseline to measure targeted reductions.

AIM To describe the use of antimicrobial drugs for food animals in New Zealand, based on sales data reported to government for 2005-2018, to provide a baseline to determine the success of measures to reduce antimicrobial use for food animals and to compare usage to selected European countries. METHODS Data were sourced from official government and industry reports to update previous estimates of use (as amount sold) of antimicrobial products applied to animals in New Zealand. The data included antimicrobial sales and animal populations, weighted where appropriate by breed and age class. Antimicrobial use was estimated based on the amount of active ingredient sold, per kg of animal biomass standardised to the probable weight at time of treatment or lifetime average but not slaughter weight (population correction unit; PCU). New Zealand data for 2017 and 2018 were adjusted to account only for antimicrobials used for farm animals by discounting horticulture use, companion animal use and export. RESULTS Between 2014 and 2018 the estimated usage of antimicrobials in animals flattened to a 5-year rolling average of 10.40 mg/PCU. New data on use for companion animals and on exports of zinc bacitracin and tylosin, included previously in the gross New Zealand values, allow a more refined estimate of use of antimicrobials in food animals of 10.21 mg/PCU in 2018, the third lowest rate of use for countries reporting by the same methodology. The intensive industries of pigs and poultry combined use more than 500 mg/PCU whereas the extensive red meat and dairy industries use an estimated 6.25 mg/PCU. New Zealand uses proportionally more cephalosporins and macrolides, two of the critically important antimicrobial groups, when compared with European countries, but less quinolones. The most obvious difference is the extensive use of zinc bacitracin and tylosin fed to pigs and poultry in New Zealand but not in the European Union. CONCLUSIONS Use of antimicrobials in food animals has stabilised to a rate of approximately 10.2 mg/PCU. This baseline should be used by the animal health industry to measure future success in its efforts to reduce and make more refined use of antimicrobial drugs as New Zealand works to deliver the government's Antimicrobial Resistance Action Plan. High rates of use of zinc bacitracin and some critically important macrolides represent clear targets in attempts to reduce usage.