Effects of Antimicrobial Peptide Supplementation on Immune Response and Immune Organ Index in Broiler Chicks

Misuse of antibiotics has led to bacterial antibiotic resistance and antibiotic residues in meat and egg. The aim of this study was to assess the effect of dietary supplementation of chicken intestinal-derived antimicrobial peptide as an alternative to antibiotic growth promoters on the immune response of birds.

Immune organs of randomly selected birds were collected for immune organ index. Blood samples were collected for serum to measure the antibody titre against infectious bursal disease and Newcastle disease virus using ELISA. Whole blood was collected to study the cytokine gene expression (IL-17A, IFN-α, IFN-γ, TGF-β, IL-10) using Real-time PCR.

Antimicrobial peptide supplementation had no significant effect (P>0.05) on the immune organ index and serum antibody Titre against infectious bursal disease and Newcastle disease virus on the 21^st and 35^th days of the study. However, it significantly (P<0.01) downregulated the gene expression of pro-inflammatory cytokines viz., IL-17A, IFN-α, IFN-γ and upregulated IL-10 expression in peripheral blood mononuclear cells. The results suggest that supplementation of antimicrobial peptide at a level of 100 mg/kg diet improved the cell-mediated immune response in broiler chicks but would not have been sufficient to enhance the humoral immune response and immune organ index in chicks.