Background and Aim: Coccidiosis is an enteric infection caused by a protozoon (Eimeria tenella). Coccidiosis is known to have a negative impact on the economy. Coccidiosis is controlled using anticoccidial drugs, antibiotics, and vaccines. Various coccidial vaccines differ in application technique, attenuation method, and the species used. Coccidial vaccines can be spray or gel-based (Form). This study aimed to compare the effect of application and approaches between spray and gel vaccines for coccidiosis. Materials and Methods: Specific pathogen-free chicks were vaccinated with different vaccines. Fecal samples were taken on 21 days post-vaccination for vaccine take, and then a challenge test was done on day 21. Results: Post-vaccination oocyst counts in gel vaccinated groups were more than the spray vaccinated ones as it recorded (1400 and 2200) oocyst/g, but the gel vaccines resulted in lower post vaccinal titer which was (10000 and 12500) oocyst/g. Results of quantitative real-time polymerase chain reaction test post-vaccination were (23.72, 20.29) cycle threshold (CT) for spray vaccines and (18.75, 17.62) CT for gel vaccinated group. By challenging all the experimental groups, the microscopic and macroscopic lesion of gel vaccines resulted in score 1, while spray vaccines groups recorded score 2 and the control non-vaccinated challenged chickens showed score 4. The non-vaccinated/non-challenged group recorded a score of zero. Conclusion: These results can help poultry producers to decide which delivery system will provide the best results for their production system. The gel vaccines showed a better protection rate and lower shedding, which means more protection of birds and public health.

Maternally derived antibodies (MDA) are a major problem for the application of NDV-vectored vaccines in commercial chickens with high levels of MDA, which could impair its efficacy. In this study, we assessed the effectiveness of different commercial vectored ND in broilers chicks with MDA against local heterologous NDV genotype VII. For this purpose, Two hundred and forty one day old chicks were divided into eight groups (30 chicks/group) (G1, G2, G3, G4, G5, G6 and G7) vaccinated with four different recombinant ND vaccines using different vaccination scheme. In addition, Group 8 (30 chicks) kept as a control non-vaccinated group. Efficacy of this type of vaccine is evaluated routinely by vaccination-challenge test. ELISA test were used for detection antibodies from collected sera of all chickens groups. Challenge test were applied at 31th day's old age of chickens. To calculate viral Shedding, cloacal swabs were collected from all groups and examined by real time RT-PCR. Obtained results for G8 (control) was recorded high antibody titer at one day but decreased gradually till become negative at 24 day old. While vaccinated groups exhibited antibody titers at 38 days old which were 3.6, 3.7, 4, 3.7, 3.66, 3.77, and 3.3 for G1, G2, G3, G4, G5, G6 and G7, respectively. Protection% of vectored ND vaccines groups ranged from 80 to 95 % despite inactivated ND vaccine recorded 60%. It was concluded that the recombinant ND vectored vaccines more potent than inactivated one in broiler chickens with MDA. Administration of rFowl-Pox+ND vaccine at 10 day exhibited higher immune response and conferred more protection and reduction of viral shedding in comparison to vaccinated at hatchery. Using rHVT+ND vaccine in one day old chicks confer optimum immune response and protection% in presence of MDA. Prime-boost vaccination strategy can overcome the problem of MDA in broiler chickens vaccination. So, it was recommended to measure the level of MDA in offspring to determine the ideal time for vaccination