Data Sheet 1_A mixed method approach to analysing patterns and drivers of antibiotic use and resistance in beef farms in Argentina.zip

IntroductionAntimicrobial resistance is a challenge to be faced by all livestock sectors; within beef farming, antibiotic use patterns vary by country and management practices. Argentina is a country with high beef production & consumption but limited information surrounding antibiotic use. The aims of this project was to understand how antibiotics are being used across the beef industry in Argentina and exploring drivers of usage.
MethodsQuantitative and qualitative data was collected by: A survey of breeding and feedlot farms including antibiotic use (from purchase data); a detailed analysis of two feedlot farms’ therapeutic antibiotic use records; a survey of vets’ views on certain antibiotic practices; and a focus group of farmers and vets focusing on wider influences affecting decision making. Antibiotic use data was calculated using mg/population corrected unit (PCU) (ESVAC) and thematic analysis was used to identify drivers of antibiotic use among participants.
ResultsThe median use across 17 farms that supplied purchase data was 76.52  mg/kg PCU (ESVAC; IQR  =  36.81  mg/kg PCU [ESVAC]). The detailed farm records showed that the largest reason for treatment was group treatments (72.92% of treatments) followed by treatment for respiratory disease (12.75% of treatments). Macrolides accounted for 76.37% of treatments. Nearly half of farms used routine prophylactic treatment for arriving animals (n  =  7/18). The use of quarantine and ‘sick pens’ were seen as important by surveyed vets with antibiotic prophylaxis and in-feed antibiotics seen as contributors to antibiotic resistance. The focus group highlighted the influence of the economic and political landscape on husbandry practices and the responsibility the farming sector had towards antibiotic stewardship.
DiscussionOverall, Argentine beef feedlots resemble North American beef feedlots in terms of antibiotic practices but with considerably lower usage, with in-feed monensin representing a large proportion of total ABU. The adaptation period presents a challenge to animal health; antibiotics are administered a prophylaxis, metaphylactic and individual treatments depending on farm management practices. Further research into internationally comparable measures of ABU and detailed cost-benefit analysis of practical, on-farm interventions are needed to aid improved antimicrobial stewardship in livestock systems globally.

【引言】抗菌素耐药性（antimicrobial resistance）是所有畜牧行业均需应对的共性挑战；在肉牛养殖领域，抗生素使用模式因国家差异与管理实践不同而有所区别。阿根廷作为肉牛生产与消费大国，其抗生素使用相关的公开信息却相对匮乏。本研究旨在厘清阿根廷肉牛全产业链的抗生素使用现状，并探究其使用驱动因素。

【方法】本研究通过以下途径收集定量与定性数据：一是针对育种场与育肥场（feedlot）开展调研，涵盖基于采购数据的抗生素使用情况；二是对两家育肥场的治疗性抗生素使用记录进行详细剖析；三是调研兽医对特定抗生素使用实践的看法；四是组织养殖户与兽医共同参与焦点小组讨论，聚焦影响决策的各类深层因素。抗生素使用数据以每群体校正单位毫克数（mg/population corrected unit，PCU）（ESVAC标准）进行核算，并通过主题分析法识别参与者群体中抗生素使用的驱动因素。

【结果】17家提供采购数据的养殖场的抗生素使用中位数为76.52 mg/kg PCU（ESVAC标准；四分位距IQR=36.81 mg/kg PCU [ESVAC]）。详细的农场记录显示，占比最高的治疗方式为群体治疗（占总治疗次数的72.92%），其次为呼吸道疾病治疗（占12.75%）。大环内酯类药物（macrolides）占总治疗用药的76.37%。近半数养殖场（n=7/18）会对新进畜禽实施常规预防性治疗。受访兽医认为，隔离措施与“病畜隔离栏”的设置至关重要，同时指出抗生素预防性使用与饲用抗生素是导致抗菌素耐药性的重要诱因。焦点小组讨论强调，经济与政治环境会对养殖实践产生影响，同时畜牧行业需承担起抗生素管理（antibiotic stewardship）的相关责任。

【讨论】总体而言，阿根廷肉牛育肥场的抗生素使用实践与北美肉牛育肥场较为相似，但整体使用量显著更低，其中饲用莫能菌素在总抗生素使用量中占比极高。畜禽适应期的动物健康管理面临挑战；根据农场管理实践的差异，抗生素可被用于预防性治疗、群体性预防治疗以及个体治疗。未来需进一步研究抗生素使用（antibiotic use, ABU）的国际可比衡量标准，并针对实用的农场现场干预措施开展详细的成本效益分析，以助力全球畜牧系统的抗菌素管理水平提升。