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Abstract
Campylobacter jejuni is the leading cause of gastrointestinal disease worldwide. Threeexperiments were done to evaluate the effectiveness of feed additives in decreasing Campylobacter
jejuni load and to understand the changes in the gut microbiota, gut function, and short-chain fatty
acid concentration in broilers. In the first experiment, the C. jejuni challenge didn’t affect bird
performance compared to the control group. In the ileum, C. jejuni didn’t affect microbial
composition and function compared to the control group. In the ceca, C. jejuni challenge increased
(P= 0.09) the relative abundance of Cyanobacteria and decreased (P=0.09) the relative abundance
of Lactobacillales compared to the control group. The C. jejuni challenge didn’t affect the
microbial function and short-chain fatty acids concentrations compared to the control group. In the
second experiment, synbiotic supplementation significantly (P=0.03) improved the feed
conversion ratio on day 28 by 16 points compared to the control group. Synbiotic supplementation
increased (P= 0.09) the relative abundance of Enterococcaceae and Staphylococcaceae and
decreased (P =0.05) the relative abundance of Enterococcus cecorum compared to the control
group. Furthermore, synbiotic supplementation upregulated (P=0.08) pathways related to amino acid biosynthesis and carbohydrate degradation compared to the control group in the ileum .
Synbiotic supplementation significantly (P=0.04) increased the acetate concentration compared to
the control group. In the ceca, synbiotic supplementation increased (P= 0.05) the relative
abundance of Ruminococcaceae and Gemmiger_A_73129 and decreased (P = 0.08) the relative
abundance of Faecalibacterium sp002160895 compared to the control group. In the third
experiment, synbiotic supplementation improved bird performance parameters on days 28 and 35
compared to the non-supplemented groups. In the ileum, synbiotic supplementation altered alpha
diversity indices compared to non-supplemented groups. An interaction effect was observed as
synbiotic supplementation decreased (P = 0.09) the relative abundance of Bacteroidota,
Ruminococcaceae, Faecalibacterium, Gemmiger_A_73129, Negativibacillus compared to the C.
jejuni group. In the ceca, C. jejuni challenge decreased (P=0.09) the relative abundance of
Anaerotruncus colihominis, Faecimonas sp900554315, Intestinimonas butyriciproducens and
Enterenecus faecium and increased (P = 0.03) the relative abundance of Bacteroides_H
thetaiotaomicron and Bacteroides_H fragilis compared to the control group. On day 28, synbiotic
supplementation increased the production of acetate (P= 0.05) and propionate (P= 0.03). Likewise,
on day 35, synbiotic supplementation increased (P=0.06) the production of isovalerate compared
to non-supplemented groups. Our studies show that C. jejuni is a near-commensal microorganism
that alters the gut microbiota and function and that synbiotics can enhance overall gut health.
Future studies aimed at understanding the interaction of C. jejuni with modified species might help
in the development of effective feed additives aimed at reducing the colonization of C. jejuni in
poultry farms.