Antimicrobials in chicken commercial feeds in Vietnam: a three-year longitudinal study before a nationwide ban of growth promoters

Abstract

BackgroundAntimicrobial growth promoters (AGPs) are included in commercial animal feed rations in many low- and middle-income countries (LMICs). We measured antimicrobial use (AMU) in commercial feed products consumed by 338 small-scale chicken flocks in the Mekong Delta of Vietnam, before a nation-wide ban on AGPs which is to be introduced over the coming three years. We reviewed the labels of commercial feeds and calculated amounts of antimicrobial active ingredients (AAIs) given to flocks. We framed these results in the context of overall AMU in chicken production, and highlighted those products that did not comply with Government regulations. ResultsThirty five of 99 different antimicrobial-containing feed products (35.3%) included at least one AAI. Eight different AAIs (avilamycin, bacitracin, chlortetracycline, colistin, enramycin, flavomycin, oxytetracycline, virginamycin) belonging to 5 classes were identified. Brooding feeds contained antimicrobials the most (51.2%), followed by grower (34.6%) and finisher feeds (12.5%). The average amount of AAIs given to flocks per kg of chicken at consumption time was 84.8 (SEM ±9.3mg). Quantitatively, chlortetracycline was consumed most (42.2mg/kg SEM ±0.34; 50.0% of total use), followed by enramycin (18.4mg SEM ±0.03, 21.8%) and bacitracin (16.4mg SEM ±0.20, 19.4%). Antimicrobials in commercial feeds were more commonly given to flocks in the earlier part of the production cycle. A total of 10 (9.3%) products were not compliant with existing Vietnamese regulation (06/2016/TT-BNNPTNT) either because they included a non-authorised AAI (4), had AAIs over the permitted limits (4), or both (2). Conclusions and recommendationSome commercial feed formulations examined included colistin (polymyxin E), a critically important antimicrobial of highest priority for human medicine. A tenth of the formulations examined did not comply with Government regulations. We estimated that consumption of AGPs in feed represented ~10% of total AMU in chicken production. We advocate for restrictions on AMU in chicken production that go beyond phased bans on AGPs. Furthermore, these steps could be bolder and implemented without unnecessary delay. Results from this study should help encourage discussion about policies on AGPs in LMICs.