| As the most widely used and effective probiotics, lactic acid bacteria which can produce antimicrobial substances to inhibit the growth of pathogenic bacteria by occupying and can also stimulate the immune system to improve immunity, is the first strain applied to microecologics.In this test, Lactobacillus was made into suspension of lactic acid bacteria to spray chicks for 1~7 day-old and inject attenuated NDV in 7-day-old chicks for studying its impact on flora diversity of chicken respiratory, immune function and protection rate against attenuated NDV and determining if the lactic acid bacteria can promote immune function of chicken respiratory tract and can be related to the flora diversity. This test would further reveal the relationship between the lactic acid bacteria and the flora diversity and immune function of chicken respiratory tract, and provide a theoretical basis for the application of spraying lactic acid bacteria as probiotics into poultry industry.600 one-day-old healthy non-immune Hailan brown-egg chicks were selected in the test, which were randomly divided into four groups. Group A was the control group fed on normal drinking water and the basal diet; group B was the group of lactic acid, sprayed by lactic acid living bacteria at 1~7day-aged and at the age of 7 days dripped saline into nose and eyes; group C was the group of attenuated NDV fed normally at 1~7day-aged, at the age of 7days immune attenuated NDV was dripped by nasal and eye drops; group D was the group of lactic acid plus attenuated NDV, sprayed by lactic acid living bacteria at 1~7day-aged and at the age of 7days immune attenuated NDV was dripped by nasal and eye drops. The test lasted for 42 days to research the effect of lactic acid bacteria on flora diversity of chicken respiratory tract, immune function of chicks and protection rate of NDV.Test results are as followed:(1) In PCR-DGGE, it was showed that the impact of lactic acid bacteria on chicken respiratory tract was obvious, but could inhibit E. coli colonization of the respiratory tract; attenuated NDV could inhibit the colonization of opportunistic pathogens, Acinetobacter in chicken respiratory tract; the results of PCR-DGGE bands sequencing are: four kinds of Pseudomonas, Escherichia, Robinsoniella sp, and Acinetobacter sp.(2) Indirect ELISA test showed that compared with the group A, 1~7 day-old chicks were sprayed by lactic acid and at the age of 7 days immune attenuated NDV being dripped by nasal and eye drops, the IgA, IgG antibody levels of their serum, throat eluent, trachea eluent, and lungs eluent were increased at different levels; the result of paraffin section and HE dyeing showed that the number of chicks bubbly mucus glands in pseudostratified epithelium of group D was significantly higher than the other groups(P <0.05), the number of chicken thin slice vesicular glands in pseudostratified epithelium of group A is less; chicks lung slices lymphoid tissue is less, and compared with group A, in group B and C lung lymphoid tissue was more dense; in group D lymphoid tissue in lung was significantly higher than the other groups and the distribution was very dense. Lactic acid bacteria could stimulate chicken respiratory tract to secrete vesicular mucus gland, increase adhesivity of epithelian ciliary;the lung of the chicks which was sprayed was with more lymphoid tissue for antigen recognition and so increased the imunity ability to against NDV.(3) This test confirmed that lactic acid bacteria could enhance the function of body’s respiratory immune system and promote the role of attenuated NDV against NDV and improve its protection rate.These results indicated that lactic acid bacteria could regulate flora diversity of chicken respiratory tract, promote chicken respiratory immune function and NDV immune protection rate. |
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