Evaluation of the efficacy of an oil-emulsion bacterin for protecting chickens against Salmonella enteritidis.

To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment.