Efficacy of formalin and gamma ray attenuated coccidial vaccines produced from local isolates against challenge infection in broiler chicken
| dc.contributor.advisor | Professor Getachew Teref | |
| dc.contributor.author | Melaku Yismaw | |
| dc.date.accessioned | 2025-12-01T08:51:42Z | |
| dc.date.available | 2025-12-01T08:51:42Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | Poultry coccidiosis, a major intestinal parasitic disease caused by Eimeria, has developed drug resistance, but vaccine use in Ethiopia remains limited. This study aimed to evaluate safety and efficacy of formalin and gamma ray attenuated coccidial vaccines produced from local isolates against challenge infection in broiler chickens. Oocysts were purified from infected poultry farms for propagation in chickens and purified, and used to develop attenuated vaccines via formalin (1.2%) and gamma ray (150 Gray). The acute vaccine safety test of both vaccines showed mild clinical coccidiosis, indicating the vaccines were safe. In a randomized control trial, 150 day-old Cobb500 chickens were divided into ten groups of 15 chickens (five in three replicates). The chickens received either formalin (FR) or gamma ray (GR) vaccines at two doses (500 and 1000) with challenge and nonchallenge groups. Vaccines were given orally on days 4 and 11 at the same dose, and challenged with 1×105 virulent oocysts on 21 day of age. The control group included non-vaccinated challenged control (NV-PC) and non-vaccinated non-challenged (NVNC). Clinical signs, oocyst output, weight gain, survival rate and intestinal lesions were monitored. Vaccine efficacy was evaluated using anticoccidial index (ACI), relative oocyst production (ROP), percent optimum anticoccidial activity (POAA) and reduction of lesion score (RLS). The result revealed that both vaccine types induced mild infection after vaccination. While post-challenge, vaccinated chicks showed mild clinical signs, reduced oocyst output, higher weight gain, 100% survival rate and reduced lesion score compared to NV-PC group. Among vaccinated groups, the one that received 1000 - radiated oocysts (GR1000) had the lowest oocyst output and higher weight gain than others (p<0.05). Vaccine efficacy index showed that GR1000 group had the highest efficacy with higher ACI (>180), low ROP (<15%), high POAA and RLS (>50%), while GR500 also performed well. In contrast, groups that received oocyst attenuated using formalin (FR1000 and FR500) exhibited limited or no protective efficacy. In conclusion, -ray attenuated sporulated oocysts can be a good candidate for producing an effective anti-coccidial vaccine from local strains of the parasite. Further study is required to test different doses, routes of administration and the shelf life of the product under different temperatures | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/7561 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Abeba University | |
| dc.subject | Attenuation | |
| dc.subject | Chicken | |
| dc.subject | Coccidia | |
| dc.subject | Efficacy | |
| dc.subject | Formalin | |
| dc.subject | Gamma ray | |
| dc.title | Efficacy of formalin and gamma ray attenuated coccidial vaccines produced from local isolates against challenge infection in broiler chicken | |
| dc.type | Thesis |