Study On Screening The Key Microbes Mediating Bursa B Cells In Early Broiler

The bursa of Fabricius is an organ unique to birds which presents a microenvironment for B-cell development.As an important humoral immune organ in poultry,bursa of Fabricius is essential for the prevention and treatment of avian diseases.The size of bursa in poultry varies significantly with age,which is characterized by progressive degradation with sexual maturity.Interestingly,as the birds grow into adulthood,the abundance and diversity of their intestinal microbes also tend to be stable.Recently,studies have found that intestinal microbes and the host immune system have evolved synergistically.Intestinal microbes play an important role in promoting the development of the immune system and regulating immune cell’s function.However,whether the intestinal microbes are involved in the regulation of B-cell in bursa of Fabricius of early broilers is not yet clear.Therefore,this study explored the production process and regulation mechanism of B-cell in bursa of Fabricius of early broilers from the perspective of intestinal microbiology.This study is mainly divided into the following two parts:(1)The bursal structure,B-cell abundance,intestinal microbial composition and abundance in different growth stages of Huiyang beards chicken:At days 1-112,the bursa of Fabricius became heavy and large rapidly with its internal structure constantly improving;at days 112-154,the bursa of Fabricius began to shrink and degenerate,of which the weight decreased and the size became smaller,with the internal follicles gradually shrinking.B-cell appeared at day 1,and the abundance of different B-cell varied:Ig M~+>Ig G~+>Ig A~+.At days 1-70,the abundance of B-cell increased rapidly,mainly distributed in the medulla of the bursa of Fabricius;at days 70-154,along with the process of atrophy and degeneration of the bursa of Fabricius,the number of three B-cell in the follicles gradually decreased.The microbialα-diversity analysis showed that with broilers sexually maturated,the diversity of intestinal microbes tends to be stable,and the microflora clearly distinguished in different periods.The variation rule of microorganism with time was similar with that of three B-cell,indicating that intestinal microbes may participate in the differentiation process of B-cell.(2)Effects of antibiotics treatment on the number of B-cell in bearded chickens:antibiotics in feed had no significant effect on the weight of broilers,and the size and weight of bursa in different ages,but the abundance of B-cell in bursa reduced significantly at days 49 and 140(P<0.05).In addition,the result of the intestinal microbes of broiler showed that,at the phylum level,the proportion of Bacteroidetes decreased significantly after antibiotics treatment(P<0.05).In comparison with the control group(CK),at the genus level,the abundances of Bacteroides and Faecalibacterium in the antibiotic group(AT)reduced significantly(P<0.05).Correlation analysis showed that Bacteroides and Faecalibacterium were significantly correlated with B-cell(P<0.05),suggesting that these two bacterial genera may be involved in the regulation of B-cell function in early broilers.To sum,this paper systematically studied the changes of B-cell abundance and intestinal microbial composition in bursa in the different growth stages of early broilers,and screened the key microbes that affect B-cell function via Correlation analysis.This study provided a scientific basis and new information for rational application of feed microecological agent to mediate humoral immunity of broilers.