Abstract
This study evaluated the effects of Saccharomyces cerevisiae-fermentation-derived postbiotic (SCFP) on pathogenic and antimicrobial-resistant (AMR) bacteria in sows within a high biosecurity system. Thirty sows were divided into three groups: a standard basal diet (CON group), CON with 1.0 kg/MT beta-glucan 50% (BG-50 group), and CON with 2.0 kg/MT SCFP (SCFP group). Fecal samples were collected at day 0, 60 days of gestation, and farrowing for enumeration of Escherichia coli and isolation of Salmonella. Isolates were assessed for AMR and antimicrobial resistance genes (ARGs) using disk diffusion and polymerase chain reaction (PCR) methods. The results showed that E. coli counts (log10 CFU/g) were significantly reduced in the SCFP group compared with the CON group (p=0.03). The SCFP decreased the frequency of E. coli isolates with resistance to chloramphenicol and tetracycline (p<0.05), while BG-50 reduced resistance to chloramphenicol, doxycycline, erythromycin, trimethoprim-sulfamethoxazole, and tetracycline (p<0.05). The mean inhibition zone for most antimicrobials against E. coli increased with gestation (p<0.05). Overall, dietary SCFP supplementation alleviated E. coli counts and the frequency of Salmonella. In addition, the effect of dietary SCFP and BG-50 supplementation on the level of AMR in E. coli and Salmonella was observed.