| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 91 === The aim of this study was to evaulate the possibility of Lactobacillus reuteri Pg 4 strain, which was isolated from the GI tract of health poultry, for use as probiotics. The Pg 4 and LCP 1 strain, which were isolated from the GI tract of poultry and commercial product respectivily, were characterization analysis by in vitro. In the capability of tolerance to acid experiment, the Pg 4 strain viable counts were maintain 109 cfu/mL after one and three hours under incubating in pH 2.0, but the viable counts of the LCP 1 strain was decreased 1 log cfu. The result showed the Pg 4 strain''s capability for surviving acidic conditions was better than the LCP 1 strain. The capacity of bile tolerance of the Pg 4 and LCP 1 strain were 68.2 and 59.5% respectivity. It showed that the Pg 4 strain was capacity of bile tolerance better than the LCP 1 strain. For adhesive ability assay, the Pg 4 strain could adhere to crop squamous and intestine epithelial cell of broiler. The LCP 1 strain could adhere to crop squamous cell but not to intestine epithelial cell. After incubating for 24 hours, the viable counts of the Pg 4 strain were 109 cfu/mL and the LCP 1 strain was 1011 to 1012 cfu/mL. The LCP 1 strain grew faster than the Pg 4 strain. The two strains were able to inhibit Escherichia coli (CCRC10675), Salmonella typhimurium I50, and Salmonella typhimurium 29E. The Pg 4 strain could resist Streptomycin, Erythromycin, Tetracycline, and Oxytetracycline. The LCP 1 strain could resist Neomycin, Streptomycin, and Gentamicin. Both of the two strains could not resist Penicillin. After the above in vitro test, the Pg 4 and the LCP 1 strains were taken orally by SPF broiler experiment. The results showed Lactobacillus counts on content and intestine wall of broiler of the Pg 4 group and the LCP 1 group were significantly higher than control (P < 0.05). And Lactobacillus counts of the Pg 4 group were higher than the LCP 1 group. Lactobacillus counts of broiler excreta of the two treatment groups in first day were the highest. The Pg 4 and the LCP 1 strain in the broiler intestine were detected by using colony-PCR methods. The results showed that the two strains were able to pass through and to survive in the GI tract of chicken. Further, the effect of the Pg 4 strain powder (108 cfu/g) on the growth performance of broiler was studied under conventional feeding environment. The results showed Lactobacillus counts in the content of crop, ileum and caecum in the Pg 4 group were higher than the control group, on 1, 3, 7, 14, 28 and 42 day-old. The body weigh gain and feed conversion of the Pg 4 group were also better than control group during growth and fasting periods. The Pg 4 strain was detected in GI tract content of the treated chicken by PCR with species-specific primers. Additionally, one day-old chickens swallowed the Pg 4 strain powder, then challenged with 106 cfu of Sal. typhimurium 29E at day 3. The results showed the Pg 4 strain reduced crop and caecal Sal. typhimurium 29E concentration and increased mucosa height in caecum. From the results described above, the Pg 4 strain isolated from the GI tract of poultry has abilities of pH, bile tolerance, adherence to the intestine epithelial cell, and inhibit E. coli、Sal. typhimurium I50 and Sal. typhimurium 29E. The Pg 4 strain can survive in the GI tract of specific pathogen-free (SPF) chickens and chickens which rearing in conventional feeding environment, and has better growth performance. It also can competitive exclusion Sal. typhimurium 29E. It shows the Pg 4 strain can be as a candidate strain for probiotic use.
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