One hundred day old broiler chicks at the age of two days were randomly divided into four groups A, B, C and D. Group B, C and D were vaccinated orally with Cocci-vac on 3rd, 10th and 20th day of age respectively, while group A was kept as non-vaccinated control. At the age of 35 days, all the birds of each group were challenged with coccidial oocysts and the effects of Cocci-vac in controlling coccidiosis in broiler chicks as well as its effects on immune response and growth traits were studied.

The immunogenic effects of Cocci-vac were recorded by challenging the birds with sporulated oocysts. In vaccinated groups (B, C and D) the immunity was better than non-vaccinated control group (A), as there were reduced or no signs of coccidiosis in vaccinated groups. The data obtained from oocysts count per gram of feces showed that the number of oocysts was 28290 and 33830 in group A (control) and 14685 and 16480 in group B (vaccinated) on 7th and 10th day post challenge, while group C had not shown any oocysts count throughout the experimental period. However, group D had shown oocysts count 3240 on 10th day post challenge but not on 7th day. The data obtained from analysis of antibody titers against Newcastle disease on 14th, 28th and 42nd day of experiment, revealed that the GM HI titers of group A (control) was slightly better (181 and 119.4) than other groups B (168.9 and 104), C (104 and 78.8) and group D (168.9 and 55.7) on 14th and 28th day but the lowest (9.8) in group A on 42nd day than other groups B (14.9), C (19.7) and D (13.9). The gross pathological study of intestine showed serosal changes (inflammation and haemorrhages) and mucosal changes (thickened wall, haemorrhages and blood tinged contents), while liver showed discolouration. These changes were much prominent in group A as compared to group B. Spleen and bursa of Fabricius represented no lesions. The data obtained by analysis of weight gain and FCR showed better weight gain (1614, 1783 and 1720) in groups B, C and D respectively and FCR 2.35, 2.24 and 2.26 in groups B, C and D respectively, in vaccinated groups as compared to control .group 'A' (Weight gain 1301 and FCR 2.45). However, within the vaccinated group C showed the best results.