Document Type Master's Dissertation Author Purchase, Cromwell email@example.com URN etd-08122008-102632 Document Title The oral application of the Onderstepoort biological products fowl typhoid vaccine, its safety, efficacy and duration of protection in commercial laying hens Degree MSc (Veterinary Science) Department Production Animal Studies Supervisor
Advisor Name Title Dr J Picard Co-Supervisor Dr S P R Bisschop Supervisor Keywords
- serum agglutination test
- euthanased at timed intervals
- orally vaccinated groups
- Salmonella gallinarum infections
Date 2006-11-24 Availability unrestricted AbstractThis project was undertaken to establish whether the Onderstepoort Biological Products Fowl Typhoid (OBPft) vaccine registered as an injectable vaccine was effective and safe when administered orally to commercial layers. Its efficacy and duration of protection were compared to the intramuscular injectable route. Commercial brown layer hens were used as they were found to be highly susceptible to Salmonella gallinarum infections.
In the safety trial birds were euthanased at timed intervals spanning 4-weeks post vaccination. Necropsies were performed and samples were taken and tested. No clinical signs or mortalities could be attributed to the OBPft vaccine. No active shedding of the vaccine strain could be detected. Slight pathological changes were noted with both routes of vaccination; however these changes were transient, returning to normal within the observation period. The injected group showed a better serological response with the serum agglutination test than the orally vaccinated groups.
In the duration of protection trial the two routes of vaccination were compared, the birds were challenged at three 8-week intervals post vaccination. All the unvaccinated birds died. The protection offered to the vaccinated groups was good when birds were challenged 8 and 16-weeks after vaccination. However, this dipped steeply by the challenge 24-weeks post vaccination. Statistically (ANOVA, p<0.05) it was found that there was no significant difference between the protection offered by either the oral or injected route of vaccination with the OBPft vaccine.
© University of Pretoria 2006
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