: Impact of Raised Without Antibiotics Measures on Antimicrobial Resistance and Prevalence of Pathogens in Sow Barns

In this study, the emergence of AMR and abundance of pathogens were investigated in sow raised without antibiotics (RWA) barns. Over a 13-month period, fecal and nasopharynx samples were collected at 3-month intervals from sows raised in RWA barns and sows in conventional barns using antibiotics in accordance with the new regulations (non-RWA). Whole-genome sequencing (WGS) was used to determine the prevalence of AMR and the presence of pathogens in these samples. Metagenomic analyses demonstrated increased abundance of pathogenic Actinobacteria, Firmicutes and Proteobacteria in the nasopharynx microbiome of RWA sows relative to non-RWA sows. However, WGS analyses revealed that the nasal microbiome of sows raised under RWA production exhibited a significant increase in the frequency of resistance genes coding for B-lactam, MDR and tetracycline.