Abstract
Microcin C7 is an antimicrobial peptide produced by Escherichia coli, composed of a heptapeptide with a modified adenosine monophosphate. This study was performed to evaluate the effects of Microcin C7 as a potential substrate to traditional antibiotics on growth performance, immune functions, intestinal barrier, and cecal microbiota of broilers. In the current study, 300 healthy Arbor Acres broiler chicks were randomly assigned to one of five treatments including a corn–soybean basal diet and basal diet supplemented with antibiotic or 2, 4, and 6 mg/kg Microcin C7. Results showed that Microcin C7 significantly decreased the F/G ratio of broilers; significantly increased the levels of serum cytokine IL-10, immunoglobulins IgG and IgM, and ileal sIgA secretion; significantly decreased the level of serum cytokine TNF-α. Microcin C7 significantly increased villus height and V/C ratio and significantly decreased crypt depth in small intestine of broilers. Microcin C7 significantly increased gene expression of tight junction protein Occludin and ZO-1 and significantly decreased gene expression of pro-inflammatory and chemokine TNF-α, IL-8, IFN-γ, Toll-like receptors TLR2 and TLR4, and downstream molecular MyD88 in the jejunum of broilers. Microcin C7 significantly increased the number of Lactobacillus and decreased the number of total bacteria and Escherichia coli in the cecum of broilers. Microcin C7 also significantly increased short-chain fatty acid (SCFA) and lactic acid levels in the ileum and cecum of broilers. In conclusion, diet supplemented with Microcin C7 significantly improved growth performance, strengthened immune functions, enhanced intestinal barrier, and regulated cecal microbiota of broilers. Therefore, the antimicrobial peptide Microcin C7 may have the potential to be an ideal alternative to antibiotic.
Highlights
Antibiotics are used widely in livestock production as an effective antimicrobial drug because they play important roles in disease treatment, disease prevention, and growth promotion [1, 2]
We found that Microcin C7 increased lactate and short-chain fatty acids (SCFAs) concentrations in the ileum and cecum of broilers, which indicates that Microcin C7 has the potential to adjust the balance of the intestinal microecology and maintain gut health
Results obtained in this study indicated that dietary supplementation with Microcin C7 can strengthen immune functions, improve intestinal villus structures, enhance intestinal barrier function, and regulate composition of intestinal microbiota, which suggests its potential to improve growth performance
Summary
Antibiotics are used widely in livestock production as an effective antimicrobial drug because they play important roles in disease treatment, disease prevention, and growth promotion [1, 2]. Global consumption of antimicrobials in livestock production was approximately 131,109 tons in 2013 and is projected to be 200,235 tons by 2030 [3]. Antibiotic use brings enormous economic benefit, but excessive use can lead to development of antimicrobial resistance and drug residues in animal products consumed by humans [1, 4]. Antimicrobial resistance makes treatment of bacterial infections with antibiotics less effective and creates a significant threat to the health of livestock and humans [5, 6]. It is of great urgency to find novel alternatives for antibiotics in livestock production
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