Nguyen Van Cuong auteur aut IRD Doan Hoang Phu auteur aut IRD Nguyen Thi Bich Van auteur aut IRD Bao Dinh Truong auteur aut IRD Bach Tuan Kiet auteur aut IRD Bo Ve Hien auteur aut IRD Ho Thi Viet Thu auteur aut IRD Choisy Marc auteur aut IRD Padungtod P. auteur aut IRD Thwaites G. auteur aut IRD Carrique-Mas J. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Chicken is, among farmed species, the target of the highest levels of antimicrobial use (AMU). There are considerable knowledge gaps on how and when antimicrobials are used in commercial small-scale chicken farms. These shortcomings arise from cross-sectional study designs and poor record keeping practiced by many such farmers. Furthermore, there is a large diversity of AMU metrics, and it is not clear how these metrics relate to each other. We performed a longitudinal study on a cohort of small-scale chicken farms (n = 102) in the Mekong Delta (Vietnam), an area regarded as a hotspot of AMU, from October 2016 to May 2018. We collected data on all medicine products administered to 203 flocks with the following aims: (1) to describe types and quantities of antimicrobial active ingredients (AAls) used; (2) to describe critical time points of AMU; and (3) to compare AMU using three quantitative metrics: (a) weight of AAls related to bird weight at the time of treatment (mg/kg at treatment); (b) weight of AAIs related to weight of birds sold (mg/kg sold); and (c) "treatment incidence" (TI), or the number of daily doses per kilogram of live chicken [Vietnamese animal daily dose (ADDvetVN)] per 1,000 days. Antimicrobials contained in commercial feed, administered by injection (n = N = 6), or antimicrobials for human medicine (n = N = 16) were excluded. A total of 236 products were identified, containing 42 different AAIs. A total of 76.2% products contained AAIs of "critical importance" according to the World Health Organization (WHO). On average, chickens consumed 791.8 (SEM +/- 16.7) mg/kg at treatment, 323.4 (SEM +/- 11.3) mg/kg sold, and the TI was 382.6 (SEM +/- 5.5) per 1,000 days. AMU was more common early in the production cycle and was highly skewed, with the upper 25% quantile of flocks accounting for 60.7% of total AMU. The observed discrepancies between weight- and dose-based metrics were explained by differences in the strength of AAls, mortality levels, and the timing of administration. Results suggest that in small-scale chicken production, AMU reduction efforts should preferentially target the early (brooding) period, which is when birds are most likely to be exposed to antimicrobials, whilst restricting access to antimicrobials of critical importance for human medicine. specialized antimicrobial use chicken small-scale farms metrics quantification Vietnam VIET NAM 052 084 080 050 020 6 art. 174 [13] 2019 2297-1769 https://www.documentation.ird.fr/hor/fdi:010076153 10.3389/fvets.2019.00174 2297-1769 [F B010076153] https://www.documentation.ird.fr/hor/fdi:010076153 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-07/010076153.pdf IRD - Base Horizon / Pleins textes 2019-08-05 2025-03-04 fdi:010076153 fre