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.

Veterinary Drug Shops as Main Sources of Supply and Advice on Antimicrobials for Animal Use in the Mekong Delta of Vietnam

In the Mekong Delta of Vietnam, small-scale poultry farmers use large amounts of antimicrobials to raise their flocks, and veterinary drug shops owners and their staff are a key source of advice to farmers on antimicrobial use (AMU). We described the network of veterinary drug shops (n = 93) in two districts within Dong Thap province (Mekong Delta). We also interviewed a randomly selected sample of chicken farmers (n = 96) and described their linkages with veterinary drug shops. Antimicrobials represented 15.0% [inter quartile range (IQR) 6.0–25.0] of the shops’ income. Fifty-seven percent shop owners had been/were affiliated to the veterinary authority, 57% provided diagnostic services. The median number of drug shops supplying antimicrobials to each farm during one production cycle was 2 [IQR 1–2]. Visited shops were located within a median distance of 3.96 km [IQR 1.98–5.85] to farms. Drug shops owned by persons affiliated to the veterinary authority that did not provide diagnostic services had a higher fraction of their income consisting of antimicrobial sales (β = 1.913; p < 0.001). These results suggest that interventions targeting veterinary drug shop owners and their staff aiming at improving their knowledge base on livestock/poultry diseases and their diagnosis may contribute to reducing overall levels of AMU in the area.

Use of antimicrobials for animals in New Zealand, and in comparison with other countries

AIM

To describe the use of antimicrobial drugs for food animals in New Zealand, based on sales data reported to government, changes over time, and in comparison with other countries and human use.

METHODS

Data were sourced from official government and industry reports covering 26 European countries, Australia, Canada, New Zealand and the United States of America in 2012, the last year data were available for all countries. The data included antimicrobial sales, and animal and human populations. Antimicrobial use was estimated based on the amount of active ingredient sold, per standardised biomass (population correction unit).

RESULTS

The estimated usage of antimicrobials for food animals in New Zealand for 2012 was 9.4 mg active ingredient/kg biomass. Total sales of antimicrobials between 2005-14 increased on average by 2.5% or 1.5 tonnes per year. Over the same time total animal biomass decreased by an estimated 4.3%, with the main decrease being in sheep (25%) and beef cattle (17%), while dairy cattle increased (28%). In the countries examined, the estimated usage of antimicrobials in food producing animals in 2012 varied from 3.8 to 341 mg active ingredient/kg biomass, in Norway and Italy, respectively, with use in New Zealand being the third lowest. Usage of antimicrobials for human health in New Zealand in 2012 was estimated at 121 mg active ingredient/kg biomass, being ranked sixteenth of the countries compared. Use in humans was 12.9 times the use in animals.

CONCLUSIONS

New Zealand was the third lowest user of antimicrobials in animal production and used much less than in human medicine. This is the first report of baseline data which may be used by the New Zealand animal health industry to develop, and measure success in, approaches to maximise the life of antimicrobials for animal health and welfare.

CLINICAL RELEVANCE

New Zealand veterinarians will soon have to make changes to adopt the World Health Organisation's global action plan to manage antimicrobial resistance. Having a benchmark of current antimicrobial use will inform priorities and allow measurement of the impact of future programmes.