| The experiment was conducted to study the influence of bacillus subtilis onproduction performance and IL-2mRNAexpression in spleen of AA+broilers. Duringthe experiment, Four thousand eight hundred1-day-old AA+broilers with similarhealthy and weight were selected and randomly distributed into two treatments. Therewere three replicates in each treatment with800broilers. The reference group was fedwith the basic diet. For treatment group,500mg/kg of bacillus subtilis was added inbasic diet. Pre-feeding7days, and the feeding experiment lasted for35days. Bycomparing the production performance, biochemistry indexes, immune organ indexes,duodenal mucosa structure and microbes composition of cecum among two treatments,we could analyze the immune enhancement mechanism and growth promotingmechanism of bacillus subtilis. In addition, the expression level of IL-2mRNA inspleen was tested by real-time quantitative PCR to explore the molecular mechanismin immune enhancement regulation of bacillus subtilis. The experiment was designedto provide theoretical foundation and scientific basis for the development andapplication of bacillus subtilis, improve the production performance and immuneperformance of AA+broilers. Results are as bellow:1. Production performance: At42days old, compared with the reference group,the average weight and ADG of treatment group respectively significantlyincreasedby7.11%and6.10%(P<0.05), and feed conversion rates decreased by0.53%,survival rate increased by0.97%.2. Biochemistry indexes: At21days old, Biochemistry indexes had nosignificant differences between the reference group and treatment group. At42daysold, compared with the reference group, the thymus index, spleen index and bursaindex of the treatment group respectively increased by12.62%,9.62%and59.49% (P<0.05).3. Immune organ indexes: Compared with the reference group, serum TP andglobulin concentrations of the treatment group respectively increased by29.52%,29.85%(P<0.05); At42days old, compared with the reference group, serum TP andglobulin concentrations of the treatment group respectively increased by16.19%,16.87%(P<0.05), Through the whole process of growth, serum Albumin of thetreatment group were higher than the reference group.4. Duodenal mucosa structure: At21days old, villus length and V/C ratio wereincreased by1.05%and3.50%(P>0.05), and depth of crypt decreased by2.38%inthe treatment group, compared with the reference group. At the age of21d, villuslength and V/C ratio of the treatment group increased by12.98%and20.94%(P>0.05), and depth of crypt decreased by6.65%(P>0.05).5. Microbes composition of cecum: At42days old, the flora of Lactobacillus andbifidobacterium in cecum were increased by5.14%、4.93%(P>0.05), and the flora ofE. coli were significantly decreased by8.09%(P<0.05), compared with the referencegroup.6. Expression level: Compared with the reference group, the expression level ofIL-2mRNA in spleen obviously increased by57.66%(P<0.05).Conclusion:1. Bacillus subtilis could obviously increase final weight, ADG, and improve theproduction performance of AA+broilers.2. Bacillus subtilis could significantly improve the bursal index at42days old,and increase serum TP and globulin concentrations of AA+broilers.3. Bacillus subtilis could improve villus length and V/C ratio and decrease theflora of E. coli of AA+broilers at42days old.4. Bacillus subtilis could significantly increase the expression level of IL-2mRNA in spleen of AA+broilers. |
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