<div>Background: Coccidiosis is one of the most dangerous diseases infecting Japanese quails. This work was conducted to study the efficacy of immunization of Japanese quail against the challenge with different Eimeria species causing coccidiosis and to optimize the dose of live sporulated oocysts that give immunity without adverse effects. 
 
Methods: Dropping samples were collected from different Japanese quail pens of the Central Poultry Development Organization, Bhubaneswar, Odisha, India. Isolation, identification, single oocyst isolation and propagation were done for each species. On the 2nd day of age, Japanese quails were divided into 10 groups and orally inoculated with low doses, 100 and 1000 live sporulated oocysts, of each isolated Eimeria species separately. Four weeks post-immunization, the quails were challenged with a high dose of the respective species. Immunization efficacy was assessed regarding clinical signs, mortality rate, weight gain, feed consumption, feed conversion ratio, oocysts output, lesion scores and hematological parameters. 
 
Result: All collected samples were Eimeria positive. Three Eimeria species were isolated and identified as E. bateri, E. uzura and E. tsunodai. Experimental results revealed that the immunized quails, either by 100 or 1000 oocysts of any isolated species, showed better results compared to the challenged, non-immunized controls. The 100-oocysts dose gave better results than those of 1000-oocysts dose without significant differences. These results indicated the effectiveness of immunization as an important tool in the management of Japanese quail coccidiosis.</div>

Efficacy of Immunization of Japanese Quail (Coturnix coturnix japonica) Against the Challenge with Different Eimeria Species