| Necrotic enteritis in chickens is an inflammatory intestinal disease caused by Clostridium perfringens infection.Through colonization of the intestine,Clostridium perfringens leads to intestinal necrosis and causes diarrhea in chickens,causing huge economic losses to the poultry farming industry.With the promulgation of the global ban on antibiotics,antibiotics are no longer available as feed additives to prevent necrotic enteritis in chickens,and Chinese herbal medicines,which have their own characteristics and advantages,have attracted attention,and some reports have shown that the compounding of different Chinese herbal extracts can improve the antibacterial efficacy.In this study,licorice extract and skullcap extract were used as materials and the extracts of both were compounded at different concentrations to obtain the herbal compound.The inhibition of Clostridium perfringens in vitro and the in vivo treatment of necrotic enteritis in chickens were investigated.The active ingredients of licorice extract and skullcap extract were also determined by high performance liquid chromatography,and the quality control of licorice extract and skullcap extract was carried out,aiming to provide a theoretical basis for the treatment of necrotic enteritis in chickens with traditional Chinese medicine.The main findings were as follows:1.The minimum inhibitory concentration(MIC)of licorice extract against Clostridium perfringens was 8 mg/m L and the minimum bactericidal concentration(MBC)was 32 mg/m L;the MIC of skullcap extract against Clostridium perfringens was 4 mg/m L and the MBC was 16 mg/m L;the content of active ingredients of licorice extract and skullcap extract was determined,and the results showed that The contents of Liquiritin apioside,Liquiritin,Liquiritigenin,Glycyrrhizic acid in licorice extract were 3.09%,2.81%,1.71%,and 9.91%.The contents of Baicalin,Wogonoside,and Baicalein in skullcap extract were 6.41%,1.60%,2.00%.And there was no significant difference between the same active ingredients in the 10 batches of licorice and skullcap extracts.2.When licorice extract at 1 mg/m L and skullcap extract at 0.5 mg/m L were compounded to inhibit the growth of Clostridium perfringens,this was the MIC combination of the two compounds,and showed synergistic inhibition on Clostridium perfringens;when licorice extract and skullcap extract were compounded at 8 mg/m L and8 mg/m L,respectively,this was the MBC combination;the licorice and skullcap compound causes bacterial death by disrupting the cell membrane of Clostridium perfringens,leading to the exocytosis of proteins.It also inhibits the formation of bacterial biofilm,increases the hydrophobicity of cell surface,and reduces bacterial adhesion and normal physiological metabolic growth.3.The addition of a certain dose of Chinese herbal compound(1 000 mg/kg)to the feed improved the clinical symptoms of necrotic enteritis in chickens caused by Clostridium perfringens and improved the reduction of growth performance caused by infection(P<0.05);increased the content of immunoglobulin A(Ig A),immunoglobulin M(Ig M)and immunoglobulin Y(Ig Y)in chicken serum(P<0.05)and improved Clostridium perfringens-induced intestinal structural damage in chickens,protecting the normal structure and function of the intestine;reducing the levels of inflammatory factors tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),interleukin-10(IL-10),and interferon-γ(IFN-γ)in the jejunum,improving the inflammatory response;increasing the levels of tight junction Zonula occludens protein-1(ZO-1),closure protein(Occludin),tight junction transmembrane protein-1(Claudin-1),and mucin 2(MUC2)in the jejunum to maintain intestinal integrity;affect the Beta diversity of the cecum microbiota,reduce the abundance of Proteobacteria at the level of the cecum microbiota phylum,reduce the colonization of harmful bacteria,and increase the abundance of Faecalibacterium at the genus level,which is beneficial to the growth of potential probiotics;Decrease the abundance of Ruminococcaceae to slow down the inflammatory response,decrease the abundance of Shigella to improve diarrheal symptoms,decrease the abundance of Clostridium to reduce the colonization of Clostridium perfringens and maintain the level of intestinal health. |
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