| The clinical application of probiotics has a history of many years.In particular,probiotics represented by Bacillus subtilis have been more widely used and have achieved good clinical results.This paper takes the suspected Bacillus subtilis from soil identified by biochemical reaction as the research object.After further identification of molecular biology,Bacillus subtilis was selected.Through the study of biological characteristics and mouse safety evaluation,the selected Bacillus subtilis was selected.The strains are used in broiler production.By measuring the growth performance of broilers and the effects on some biochemical and immune indicators,a certain foundation is laid for the development and utilization of micro-ecological preparations in the later stage.The specific test methods and results are as follows:1.The 16S rRNA-based PCR identification method,amplified fragment sequence determination and homology analysis were used to determine 10 suspected Bacillus subtilis strains,and only 3 strains K4,K5and K6 were Bacillus subtilis.2.The identified 3 strains of Bacillus subtilis are tested by acid resistance,bile salt resistance,high temperature resistance and antibacterial drug susceptibility test,the result shows:K4 is compared with other two strains of Bacillus subtilis at p H 2.5,bile salt concentration 0.20%and Good tolerance at 100℃;3.These 240 hybrid broilers were randomly divided into Test Group 1,Test Group 2,Control Group and blank group,each group had three replications,each group had 20 chicks.Test 1 group was fed with Bacillus subtilis 5.0×10~6CFU prep 1ml one day,every chick;test 2 group was fed with 8.0×10~6CFU prep 1ml one day,every chick;Control group was fed with 8.0×10~6CFU prep 1ml one day,every chick;The blank group did not add anything except Basal Diet,the trial period was 28 days.（1）At the age of 14 days,the average body weight of the experimental group 2 was significantly higher than that of the control group（P<0.05）,and finally,there was no significant difference in the average total weight gain and average daily weight gain between the experimental groups and the control group（P>0.05）,while the feed-to-meat ratio of the experimental group 2 was significantly lower than that of the control group（P<0.05）.);（2）There was no significant difference in the average content of serum calcium（Ca）,albumin,CD4+,CD8+and IgM between the experimental group and the control group（P>0.05）;Serum inorganic phosphorus content of chicks in group 1 at 28 days of age was significantly higher than that in control group（P<0.05）;total protein content in serum of broilers,at 14 days of age,serum total protein content in test group 2 was significantly higher than that in control group（P<0.05）,at 28 days of age,the serum total protein content of test group 1,test group 2 and control group was significantly higher than that of the blank group（P<0.05）.At the age of 28 days,the average triglyceride content of the experimental group 2and the control group was significantly lower than that of the blank group（P<0.05）;（3）The content of IgA in the serum of broilers was significantly higher than that of the control group at the 14th and 28th days of age in the broiler chickens（P<0.05）.The average content of IgG in test group 1was significantly higher than that in control group（P<0.05）It can be seen from the results that K4 has good biological characteristics and has a significant impact on the growth performance and some serum and immune indicators of hybrid broilers,so it can be used as a candidate strain for probiotics. |
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