An experimental Salmonella Enteritidis (SE) oil emulsion bacterin (EXBAC) 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 (COMBAC) and EXBAC, respectively. All chickens were challenged at 8-week-old with broth containing 1.5x10[superscript 6] colony forming unit (cfu.) of nalidixic acid resistance SE (nalSE) by oral drop. The results revealed that rate of nalSE isolated from spleens and ceca of both vaccinated groups were significantly lower than the controls (p<0.05). Antibody against SE performed by ELISA shown that the COMVAC group had significantly higher response than other group at 6 and 8-week-old (p<0.05). No differences were observed on isolation rate and antibody response between vaccinated groups. In the second experiment, chickens were divided into 5 groups, 20 birds of each: group 1 were served as a control, groups 2 and 3 were vaccinated with COMVAC at 8-week-old and 8 and 12-week-old, respectively, groups 4 and 5 were vaccinated with EXBAC at 8-week-old and 8 and 12-week-old, respectively. All hens were challenged with broth containing 2x10[superscript 8] cfu of nalSE by oral drop at 23-week-old. The results revealed that rate of nalSE isolated from ceca of all vaccinated groups were lower than control group. The rate of nalSE isolated from shell and yolk membrane were very low and not significantly difference between groups. Antibody against SE of the COMVAC and EXBAC groups were significantly higher than control group 2 weeks postvaccination til the end of the experiment. No differences observed on antibody response among vaccinated groups.
