Antimicrobial Use in the Animal Sector in Japan from 2011 to 2022

<b>Background/Objectives:</b> Evaluating antimicrobial use (AMU) is essential in the investigation and implementation of antimicrobial resistance (AMR) prevention measures. Here, we examined AMU using an index (mg/kg biomass) that considers the antimicrobial sales volume and livestock biomass in Japan from 2011 to 2022. <b>Methods:</b> Antimicrobial sales volumes were obtained from JVARM data, and biomass data were obtained from reliable statistics. Beef cattle, dairy cattle, pigs, broiler chickens, layer chickens, fish raised in freshwater, and fish raised in seawater were targeted in this study. <b>Results:</b> Tetracycline accounted for 39%, macrolides for 18%, penicillins for 12%, and sulfonamides for 11% of the sales in 2022. The peak antimicrobial sales volume was 847 tons in 2017, and then declined to 766 tons by 2022 with fluctuations in the interim. From the perspective of mg/kg biomass, AMU tended to increase in beef cattle, dairy cattle, and fish raised in seawater, while pigs, broilers, layers, and fish raised in freshwater showed a decreasing trend. In broilers, the decreasing trend that could not be confirmed by sales amount alone was detected using the newly established index. <b>Conclusions:</b> By calculating the mg/kg biomass, it became possible to create an interpretation that is different from that of the simple sales quantity data. We believe that this indicator is stable, transparent, and easily understandable for national monitoring.