| The purpose of this experiment was to investigate the health effects of probiotics on the healthy chickens and the protective effects of probiotics on the chickens with the challenge of E.coli by observing chicken growth performance,serum immunoglobulin content,intestinal microflora abundance and structure,and Toll-like receptor protein expression.At the health care test of healthy chickens,ninety one-day-old chickens were selected and divided into a control group,a low-dose probiotic group,and high-dose probiotic group,with three replicates per group and ten replicates each.Among them,the control group was fed a basic diet,the low-dose probiotic group was supplemented with a composite probiotic 10~9cfu per kg of the basic diet,and the high-dose probiotic group was supplemented with a composite probiotic 2*10~9cfu per kg of the basic diet.On the 21st day,10 chickens from each group were lethal to death,and the required samples were collected immediately.The chickens used at the challenge test were 14-day-old white feather chickens.One hundred and twenty 14-day-old chickens were randomly divided into 6 groups,which were the control group,the model group,the natural recovery group,the probiotic prevention group,the probiotic treatment group,and the antibiotic treatment group.All the chickens ate freely and their feed intake and body weight were recorded.Blood was collected weekly,with an additional blood sample taken after the onset of challenge.The contents of serum immunoglobulin were detected by ELISA method,the structure of liver and kidney was observed by light microscope and electron microscope,the expression of XDH and GLUT-9 in liver and kidney was detected by immunohistochemistry,fluorescence quantitative PCR and protein imprinting.High throughput Sequencing was used to detect changes in the cecum microflora.The test results were as follows:At the health care test of healthy chickens,compared with the control group,the feed-to-meat ratios of the low-dose probiotic group and high-dose probiotic group were significantly reduced(P<0.05),and the serum Ig G and Ig M contents were extremely significantly increased(P<0.01).The TLR2 protein expression and relative m RNA expression in the low-dose probiotic group were significantly increased(P<0.05),and the TLR4,Myd88,TRAF-6,AP-1 protein expression and relative m RNA expression were extremely significantly increased(P<0.01);TLR2,TLR4,Myd88,TRAF-6,AP-1 protein expression and relative m RNA expression in the high-dose probiotics group were exemely significantly increased(P<0.01).Therefore,feeding probiotics can reduce the feed-to-meat ratios of white feather chickens,increase the contents of serum Ig G and Ig M,and improve the body immunity by regulating the expression of Toll-like receptor pathway proteins.At the challenge test of E.coli,compared with the control group,the feed-to-meat ratios of chickens in the model group,probiotic treatment group and natural recovery group showed a significant increase after the challenge(P<0.05).After 7 days of treatment,the feed-to-meat ratios of chickens among the probiotic prevention group,the probiotic treatment group,antibiotic treatment group and control group had no significant difference(P>0.05).The serum Ig G,Ig M,and E.coli antibodies in the model group,natural recovery group,probiotic treatment group,and antibiotic treatment group after 3 days of challenge with E.coli were significantly higher than those in the control group(P<0.05).The serum Ig G,Ig M,and E.coli antibodies in the probiotic prevention group were significantly higher than those in the control group(P<0.05)and significantly lower than those in the model group(P<0.05).After 7 days of treatment,the serum indexes in the natural recovery group were significantly higher than those of the control group(P<0.05),and the serum index of the probiotic treatment group and antibiotic treatment group were significantly higher than those in the control group(P<0.05),while significantly lower than those of the natural recovery group(P<0.05).There was no significant difference in serum indexes between the prevention group and the control group(P>0.05).Through the analysis of the high-throughput sequencing results,the duodenum microbial communities in the model group and the natural recovery group were reorganized.From the analysis of the phylum level,the numbers of thick-walled mycoplasma in the model group and the natural recovery group decreased,and the numbers of proteobacteria increased.From the subordinate level analysis,the model group and the natural recovery group showed a decrease in Lactobacillus and an increase in Enterobacter.There was no significant difference in the duodenum microbial communities among the probiotic prevention group,antibiotic treatment group,probiotic treatment group and control group.The Toll-like receptor protein distribution,m RNA relative expression,and protein expression in the model and natural recovery groups were significantly higher than those in the control group,indicating that the inflammation response was severe.The Toll-like receptor protein distribution,m RNA relative expression,and protein expression in the probiotic prevention group were not significantly different from that of the control group(P>0.05),and the differences were extremely significant compared with the model and natural recovery groups(P<0.01).The Toll-like receptor protein distribution,m RNA relative expression,and protein expression in the probiotic and antibiotic treatment groups were significantly or extremely significantly higher than those in the control group(P<0.05 or P<0.01),and extremely significantly lower than those in the model group and natural recovery group(P<0.01),showing a better treatment effect.It can be seen that adding probiotics to the diet of chickens can protect the intestinal beneficial bacteria during E.coli infection,reduce the numbers of E.coli in the intestine,and reduce the expression of Toll-like receptors during inflammation,so as to decrease the production of inflammatory factors and reduce inflammation response. |
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