Efficacy of the experimental Salmonella enteritidis oil-emulsion bacterin in preventing systemic infection and vertical transmission in laying hens
2006
Sureerat Numee(Chiang Mai University, Chiang Mai (Thailand). Faculty of Veterinary Medicine. Dept. of Food Animal) | Indhira Kramomthong(Chulalongkorn University, Bangkok (Thailand). Faculty of Veterinary Sciences. Dept. of Microbiology) | Jiroj Sasipreeyajan(Chulalongkorn University, Bangkok (Thailand). Faculty of Veterinary Sciences. Department of Veterinary Medicine)
Experimental Salmonella Enteritidis (SE) oil emulsion bacterin were prepared and tested for its efficacy in preventing systemic infection and vertical transmission in laying hens. Two experiments were conducted. Bacterin was vaccinated subcutaneously at the nape of the neck. The first experiment, chickens were divided into 4 groups, 20 birds of each at 4-week-old. Groups 1 and 2 were served as controls. Groups 3 and 4 were vaccinated with commercial vaccine (COMVAC) and experimental bacterin (EXVAC), respectively. All chickens were challenged at 8-week-old of SE by oral drop. The results revealed that rate of SE isolated from spleens and caeca of both vaccinated groups were significantly lower than the controls (p LT 0.05). Antibody against SE performed by ELISA shown that the COMVAC group had significantly higher response than unvaccinated group at 6 and 8-week-old (p LT 0.05). No differences were observed on isolation rate and antibody response between vaccinated groups. In the second experiment, chickens were vaccinated with COMVAC or EXVAC at 8-week-old and 8 and 12-week-old. All hens were challenged with SE by oral drop at 23-week-old. The results revealed that rate of SE isolated from caeca of all vaccinated groups were lower than control group. Antibody against SE of the COMVAC and EXVAC groups were significantly higher than control group 2 weeks postvaccination til the end of the experiment. There were no differences observed on antibody response among vaccinated groups. There is no definite conclusion of this study on an efficacy of EXVAC to prevent the vertical transmission of SE since the SE was present only in the yolk membrane of the control group, not in the other experimental groups.
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