A proprietary antimicrobial feed additive comprised of essential oils, medium-chain fatty acids, and a toxin-adsorbing mineral showed promising bacteriostatic and bactericidal effects in vitro. This study investigated the impacts of supplementing this blend on growth, gut microbiome, and enteric disease resilience in weaned pigs experimentally challenged with an enterotoxigenic Escherichia coli (ETEC). Thirty-six weanling pigs (6.88 ± 0.30 kg body weight) blocked by weight and gender were assigned to one of three dietary treatments: control or dietary supplementation with 0.25% or 0.50% of the antimicrobial blend. This study lasted 28 d with 7 d before and 21 d after the first ETEC inoculation (day 0). All pigs were orally inoculated with 1010 CFU F18 + ETEC/3-mL dose for 3 consecutive days. Growth performance data and diarrhea scores were recorded throughout the experiment. Fecal samples collected on days -7, 0, 7, and 21 post first inoculation (PI), and ileal digesta and mucosal tissue collected on day 21 PI were further analyzed for gut microbiome using 16S rRNA sequencing. All data, except for frequency of diarrhea and gut microbiome, were analyzed by ANOVA using the PROC MIXED of SAS. The chi-square test was used for analyzing frequency of diarrhea. Gut microbiome data were analyzed using QIIME2 and visualized using the R program. Dietary supplementation of 0.25% or 0.5% of the antimicrobial blend increased (P < 0.05) feed efficiency on days 14 to 21 PI of ETEC and reduced (P < 0.05) frequency of diarrhea during the study. Compared with the control group, adding 0.5% dietary antimicrobial blend increased (P < 0.05) relative abundance of Firmicutes but reduced (P < 0.05) Bacteroidetes and Proteobacteria in feces on day 7 PI. Pigs that received the antimicrobial blend also had higher (P < 0.05) relative abundance of Lactobacillaceae, but lower (P < 0.05) relative abundance of Enterobacteriaceae in feces on day 7 PI than pigs in control. In conclusion, supplementation of this antimicrobial blend at 0.5% reduced incidence of severe diarrhea in weaned pigs challenged with F18 ETEC and enhanced feed efficiency of weaned pigs at the last week of the experiment. Supplementation of this antimicrobial blend also modified the microbiota diversity in feces and ileal mucosa of weaned pigs.
Keywords: Escherichia coli challenge; antimicrobial feed additive; diarrhea; microbiome; weaned pigs.
This experiment aims to investigate an antimicrobial blend consisting of essential oils, medium-chain fatty acids, and a toxin-adsorbing mineral on diarrhea, growth performance, and gut microbiome of newly weaned pigs experimentally infected with a pathogenic Escherichia coli (F18 E. coli). A total of 36 weaned pigs were randomly allotted to one of three dietary treatments: (1) a complex control diet that met the nutrient requirement of weaned pigs; (2) supplementing 0.25% of the antimicrobial blend; and (3) 0.50% of the antimicrobial blend. The experiment lasted 28 d with 7 d adaptation and 21 d after the first F18 E. coli inoculation. Results of this experiment demonstrate that supplementation of this antimicrobial blend enhanced disease resistance of weaned pigs, as indicated by reduced frequency of diarrhea during the entire experimental period. An improved feed efficiency was also observed in pigs supplemented with antimicrobial blend at the last week of the experiment. In addition, feces collected on day 7 post-E. coli inoculation contained relatively more Lactobacillaceae but less Enterobacteriaceae when pigs were supplemented with this antimicrobial blend. In conclusion, supplementation of antimicrobial blend could reduce diarrhea of E. coli-infected pigs and modify fecal microbiome of weaned pigs during the peak of E. coli infection.
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