| The paper was focused on the combination three molecular biology methods (ERIC-PCR-AGE, ERIC-PCR-DGGE and V3-PCR-DGGE) and viable total count to analyse multiplicity of microorganism community in respiratory tract of broilers; the growth performance, microorganism community structure in respiratory tract, threatment and prevention Staphylococcus aureus infection of broilers were effected by the spraying agent of Bacillus subtilis PabO2. The results are reported as follows.1.48 7-day-old Avian broilers were randomly divided into four groups. Group CK was the control group, Group P was sprayed lml/m3 of the spraying agent of B. subtilis PabO2 (108cfu/ml) in the room. At the age of 28-day-old, the broilers were weighted. The results were showed that net gain of Group P increased 9.4g, average daily gain increase 2.68g, total feed consumption decreased 125g, average daily feed decreased 5.59g, F/G decreased 0.02, compared with Group CK, the differences of all were not significant (P>0.05).The results indicated that the spraying agent of B. subtilis PabO2 could improve growth performances of feed intake, daily gain and F/G to spray PabO2, but it could not play a significant role.2. Bacteria in respiratory tract of broilers at of age 28 days and 49 days were detected by viable total count and three molecular biology models.The results showed total bacterial number in respiratory tract of broilers at age of 49 days was little larger than that of broilers at age of 28 days; Total bacterial number of throat was one order higher than that of trachea, Total bacterial number of throat was 106cfu/g,that of trachea was 105 cfu/g; After spraying PabO2,Total bacterial number of throat increased significantly (P<0.05), total bacterial number of trachea increased,but not significantly(P>0.05). Bands of respiratory tract of broilers at age of 49 days were more than that of broilers at age of 28 days significantly(P<0.05), the similarity of microorganism community in respiratory tract was 59%～84%;bands of throat were more than that of trachea significantly(P<0.05),the similarity of microorganism community between throat and trachea was 60%～84%. The finding indicated that multiplicity of microorganism community in respiratory tract of broilers at age of 49 days was more than broilers at age of 28 days,multiplicity of microorganism community in throat was more than in trachea.After spraying PabO2,bands of throat increased significantly(P<0.05),similarity increased by 6～16 percentage points; bands of trachea did not increased significantly(P>0.05), similarity increased by 11～16 percentage points. The results indicated spraying PabO2 could increase number and multiplicity of bacteria in respiratory tract,however,there were different modulatory effects on different locations, modulatory effects on throat was larger than on trachea.3.Broilers of two groups were infected by Staphylococcus aureus G1,then microorganism community structure of respiratoty tract was tested by viable total count and molecular biology models.The results showed that spraying PabO2 before and after infected by G1 could not significantly change total bacterial number of throat(P>0.05),but could significantly reduce total bacterial number of trachea and Staphylococcus number of respiratory tract(P<0.05);spraying PabO2 before or after infected by G1 could not significantly change total bacterial number of respiratory tract(P>0.05),but could significantly reduce Staphylococcus number of respiratory tract(P<0.05). Spraying PabO2 before and after infected by Glor spraying PabO2 only before infected by G1 could renew the multiplicity and similarity of microorganism community,however, spraying PabO2 after infected by G1 could not do.4. The histological sections of lung were observed by optical microscope, lung tissue of broilers after spraying PabO2 was normal, alveolar did not rupture or fuse, lung interstitium did not hyperplasia, inflammatory exudation did not infiltrate,moreover,the number of lymphonodulis increased; There were ruptured and fused alveolar, inflammatory exudation and more inflammatory cells, severe haemorrhage and metaplasia in lung of the broilers infected by G1; There were more lymphonodulis instead of lung injury in the lung of broilers sprayed PabO2 before and after infected by G1; There were expanded alveolar and more inflammatory cells, but number of lymphonodulis increased in lung of broilers sprayed before infected by G1;There were ruptured and fused alveolar,inflammatory exudation,more inflammatory cells,and slight metaplasia in the lung of broilers sprayed after infected by G1. Finding indicated spraying agent of PabO2 did not injury lung tissue, on the contrary could stimulate immune function; spraying agent of PabO2 could prevent and cure respiratory disease caused by Staphylococcus aureus,and the preventive effect is better than the therapeutic effect. |
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