Effect Of Feed Additive Of Antimicrobial Peptides On Broiler’s Immune Function And Intestinal Flora

In this paper,the effect of the Brevibacillus laterosporus S62-9 antimicrobial peptides feed additive on AA+ broiler immune organs,blood biochemical and immunological indices,intestinal and intestinal microflora was studied in order to provide scientific basis for the use of the antimicrobial peptide as feed additive for livestock and poultry breeding.320 1-day-old healthy AA+ broiler were chosen and randomly divided into four groups,named low-dose group,middle dose group,high dose group and control group,respectively(antimicrobial peptides additives was not added into control group,meanwhile,the amount of additives in low-dose group,middle dose group and high dose group were 1.2%,1.7% and 2.1%,respectively).Feeding trials lasted for 42 days.Effects of antimicrobial peptides feed additive on Broiler thymus,spleen and thymus index of immune organs were measured.The results showed that the index of immune organs in all antimicrobial peptides groups were increased,especially the index of bursa.The groups of antimicrobial peptides broiler bursa index reached significant difference(P<0.05)compared with the control group,which indicated that antimicrobial peptides feed additives can improve the immunity of broilers.Blood albumin(ALB),total protein(TP),urea nitrogen(BUN),alanine aminotransferase activity(ALT),immunoglobulin A,G,M(IgA,IgM,IgG),growth hormone(GH)and the content of insulin-like growth factor-1(IGF-1)were detected.Where TP.The means of micro plate reader was used when testing ALB,Ig,GH and IGF-1,BUN using urea enzyme,ALT using Lai’s method.The results showed that the content of TP in each group of antimicrobial peptides were higher,there was significant difference(P<0.05)in which the high-dose group compared with control group;The content of ALB each group were higher,where the middle dose group and high dose group compared with the control group were significantly different(P<0.05);The activity of IgA,IgM and IgG were higher in each antimicrobial peptide groups,the activity of IgM and IgG had significantly different(P<0.05)between dose-dose group and high dose group compared with the control group,GH and IGF-1 activity of each antimicrobial peptide groups were higher and there was a significant difference(P<0.05).The broiler gut after HE staining was observed by optical microscope,it showed that the structure of intestinal mucosa of broilers antimicrobial peptide group was relatively more complete and aligned fluff was more closely.The ratio of villi length and crypt depth was improved with feeding the antimicrobial peptide,so did the length of villi,moreover,the depth of the crypt were reduced.There were different degrees of improvement in the jejunum and ileum intraepithelial lymphocyte and goblet cells.