In response to new stringent regulations in Canada regarding the use of antibiotics in animal production, many farms have implemented practices to produce animals that are raised without antibiotics (RWA) from birth to slaughter. This study aims to assess the impact of RWA production practices on reducing the actual total on-farm use of antibiotics, the occurrence of pathogens, and the prevalence of antimicrobial resistance (AMR). A 28-month longitudinal surveillance of farms that adopted the RWA program and conventional farms using antibiotics in accordance with the new regulations (non-RWA) was conducted by collecting fecal samples from 6-week-old pigs and composite manure from the barn over six time points and applying whole-genome sequencing (WGS) to assess the prevalence of AMR genes as well as the abundance of pathogens. Analysis of in-barn drug use records confirmed the decreased consumption of antibiotics in RWA barns compared to non-RWA barns. WGS analyses revealed that RWA barns had reduced the frequency of AMR genes in piglet feces and in-barn manure. However, metagenomic analyses showed that RWA barns had a significant increase in the frequency of pathogenic Firmicutes in fecal samples and pathogenic Proteobacteria in barn manure samples.

中文翻译：

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来自无抗生素饲养农场的仔猪肠道和谷仓粪肥显示抗菌素耐药性降低但病原体流行率增加

为了响应加拿大关于在动物生产中使用抗生素的新严格规定，许多农场已经实施了生产从出生到屠宰不使用抗生素 (RWA) 饲养的动物的做法。本研究旨在评估 RWA 生产实践对减少农场实际抗生素使用总量、病原体发生率和抗菌素耐药性 (AMR) 流行率的影响。对采用 RWA 计划的农场和按照新规定使用抗生素的常规农场（非 RWA）进行了 28 个月的纵向监测时间点并应用全基因组测序 (WGS) 来评估 AMR 基因的流行以及病原体的丰度。对谷仓内药物使用记录的分析证实，与非 RWA 谷仓相比，RWA 谷仓中抗生素的消耗量有所减少。WGS 分析显示，RWA 猪舍降低了仔猪粪便和猪舍粪便中 AMR 基因的频率。然而，宏基因组分析表明，RWA 猪舍的致病频率显着增加。粪便样本中的厚壁菌和谷仓粪便样本中的致病变形菌。