The present study was conducted to evaluate diclazuril at the recommended and its two folds doses (1 & 2 ppm), flavomycin at 75 gm/ton and their combinations on the immune response in chickens vaccinated with IBD vaccine. Diclazuril displayed a dose dependent immunity suppression. In the recommended dose, it did not harm the bird immunity. While, in double recommended dose, it significantly suppressed the chicken immune response to IBD virus vaccine. The depressed response was reflected as a decreased bursal weight, skin hypersensitivity, total leucocytic count, lymphocyte count, antibody titer, serum protein and serum globulins. While, flavomycin at 75 gm/ton had no detectable effect on the bird immune response to IBD virus vaccine. The combinations between diclazuril (as an anticoccidial drug) and flavomycin (as a growth promotor) have no drug interaction in our experiment.

Colibacillosis was produced experimentally in 14 white Leghorn broiler chickens by intratracheal inoculation of 0.3 ml broth of E. coli O78:K80 containing approximately 10 6 colony forming unit. Another 7 clinically normal chickens were used in this study. Ofloxacin was administered to chickens intravenously and orally (5 mg/kg b.wt.) to determine the effect of colibacillosis on its kinetic behavior.