Isolation And Identification Of Lactobacilli From The Digestive Tract Of Broilers And Study On Their Functions

With the development of breeding, probiotics are widely used and it played an important role in the healthy and sustainable development of husbandry. This study focused on the function of lactobacilli isolated from the digestive tract of broilers. The isolated were used in the feeding test on broilers. Though the test of gaining weight, the index of immune organs and the count of microbes in content of cecum, we found that lactobacilli isolated from broilers have a strengthening function on the performance and immune function of the broilers. This study provided theory and strains for research and development of lactobacilli isolated from broilersThis study was divided into three parts:Part one: The isolation and identification of lactobacilli from digestive tractsIn this study, 4 strains (named SL-1,SL-2,SL-3 and SL-4) were isolated from the mucosa of broilers'digestive tract, through dyeing, microscopic examination, biochemical test and the analysis of 16s rRNA, identification, they belong to genus of lactobacilli: L.acidophilus, L.crispatus, L.rhamnosus, L.salivarius.Part two: screening of probiotic properties and preparation of probioticsThe test of bile salt resistance, tolerance to acidic pH and antimicrobial activity was conducted in the 4 isolated strains. The results showed SL-3 strain could grow in the 0.3% oxgall broth, after being cultivated for 48 h the count could reach to 3.47×109 CFU/ml. After being cultivated for 2h in pH2.0 broth, the count could reach to 1.38×103CFU/ml. The antimicrobial action of SL-3 supernatant against pathogenic E.coli was determined by the agar diffusion method. The result showed it could inhibit the growth of E.coli. The mean diameter of inhibition zone was 21.2mm.The preparation was made with SL-3 under anaerobic circumstances. Through test of safety, storage, and count, it conformed to the quality standard and it could be used to feed to broilers.Part three: The effects of lactobacilli probiotics on broilersLactobacilli probiotics with SL-3 were fed to broilers. Through the test of gaining weight, feed/gain ratio, index of immune organs, antibody titer and count of lactobacilli in content of cecum, the effects of probiotics on performance and immune function was obtained. Two strains were used, SL-3 from broiler and CL-11 from swine. The results showed that on the 35th days the gaining weight of group fed on 0.3% SL-3 significantly higher than the control group and antibiotic group by 11.09% and 7.18%. The group fed on 0.3% lactobacilli from swine was higher than control group and antibiotic group by 4.08% and 0.42%; the group fed on 0.3% SL-3 strain increased the index of spleen, bursa, and thymus by 67.14%, 16.47%, 38.16% and 56%, 22.02%, 30.81%, respectively, compared to control group and antibiotic group. While the group fed on 0.3% lactobacilli from swine increased the above index by 31.42%, 6.82%, 9.76% and 22.66%, 11.90%, 3.92% respectively, compared to control group and antibiotic group. The group fed on 0.3% SL-3 strain increased the antibody titer by 2log2 and 1.75log2 respectively, compared to control group and antibiotic group ((P<0.05). And this group also increased the count of lactobacilli in the cecum by 1.86CFU/ml and3.09CDU/ml, decreased the count of enterobacter by 7.24CFU/ml and 2.45CFU/ml, in comparison with control group and antibiotic group. The group fed on swine lactobacilli also increased the count of lactobacilli of cecum by l.02CFU/ml and1.69CFU/ml. In other stages the group fed on SL-3 strain also improved the performance, strengthened immune function and balanced the count of normal flora of tract. The result of this study showed SL-3 strain can improve the performance and the normal flora, and it significantly better the strain from swine. The result provided theory for developing and using SL-3.