Comparative Response of the Nigerian Indigenous and Broiler Chickens to a Field Caecal Isolate of Oocysts.

Response of Nigerian indigenous (local) and broiler chickens to experimental infections was investigated by measures of clinical signs, packed cell volume (PCV), body weights (BW), feed consumption, faecal oocyst counts (oocyst per gram), and microscopic intestinal lesions. Three-week-old chickens of each breed received single pulse infections with 2500, 5000, and 100.000 sporulated oocysts. Infected birds were dull and passed bloody diarrhoea. OPG showed a dose related response but no significant difference between groups ( > 0.05). OPG was significantly higher in local chickens ( < 0.05) and varied significantly with time ( < 0.05). PCV declined significantly in infected birds within breeds and groups ( < 0.05); however, the decline in PCV was significantly greater in broilers ( < 0.05). Both breeds had significant BW gains ( < 0.05). BW gain varied between groups being significantly higher in the uninfected control broilers than in the infected broilers ( < 0.05). Comparatively, broilers gained significantly more BW than their local counterparts ( < 0.05). Feed intake increased significantly with time ( < 0.05) in both breeds. The isolate was pathogenic to both breeds of chicken although clinical signs and lesions were more severe in indigenous chickens suggesting the breed's more susceptibility.