PSV-19 Trace Amounts of Antibiotic Altered Gut Microbial Profiles of Weaned Pigs Experimentally Infected with a Pathogenic Escherichia Coli

Abstract

Abstract Our previous studies demonstrated that trace amounts of antibiotic supplements exacerbated growth performance and systemic inflammation of weaned pigs infected with a pathogenic Escherichia coli (E. coli). The objective of this study was to investigate the influence of in-feed trace amounts of antibiotic on distal colon microbiota of pigs experimentally infected with E. coli F18. Thirty-four weaned pigs (6.88 ± 1.03 kg body weight) were individually and randomly allotted to 1 of 3 dietary treatments (9 to 13 pigs/treatment). The 3 dietary treatments were basal nursery diet (control), and 2 additional diets supplemented with trace amounts (TRA; 0.5 mg/kg) or label-recommended dose (REC; 50 mg/kg) of antibiotic (carbadox), respectively. The experiment lasted 18 d [7 d before and 11 d after the first inoculation (day 0)]. The E. coli F18 inoculum (1010 cfu/3 mL) was orally provided to all pigs for 3 consecutive days. Distal colon digesta samples were collected on d 5 and 11 post-inoculation (PI), and microbial profiles were analyzed using 16S rRNA gene sequencing at the V4 hypervariable region. All compositional data were statistically analyzed using R software with QIIME2 plugin. Bray-Curtis PCoA analysis displayed those pigs in both control and TRA groups were separately clustered from REC on d 5 and 11 PI. Pigs in TRA group had a lowest (P < 0.05) relative abundance of Lactobacillaceae whereas REC group tended to have increased (P < 0.10) relative abundance of Lachnospiraceae than other treatments on day 5 PI. On day 11 PI, pigs in REC had reduced (P < 0.05) relative abundance of Prevotellaceae than pigs in CON group. In conclusion, in-feed trace amounts of antibiotic could modify gut microbiota of weaned pigs challenged with E. coli F18.