The present study was designed to evaluate the toxicopathological effects of feeding of ochratoxin contaminated feeds to broiler chicks for 21 and 35 day. Two experiments were conducted simultaneously. In these experiment six groups each having 75 chicks were maintained and offered feeds containing 0, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/kg OTA. Half of the birds from each group of both experiments were killed on days 21 and 35, respectively. Remaining birds of all the groups were switched to basal feed and killed on day 42 of the experiment. Birds killed in both experiments showed a significant decrease in the feed intake and body weight in OTA fed groups. OTA associated clinical signs and behavioral alterations included diarrhea, depression, increased water intake and ruffled feathers. The highest mortality was 12 and 20 percent observed in birds fed 0.4 and 0.8 mg/kg OTA, respectively. OTA fed birds showed a significant increase in the relative weights of liver and kidney while decrease in weight of bursa of Fabricius and thymus. Gross lesions in liver and kidney included enlargement, paler discoloration and friable consistency and hemorrhages. Microscopic changes in the kidneys included congestion and tubular epithelial cell necrosis. Liver showed vacuolar degeneration along with individual cell necrosis in birds fed 0.2-0.8 mg/kg OTA.  Birds killed on day 35 of the intoxication showed changes similar to those observed in 21 days old birds with the exception of increased severity of these alterations in 0.4 and 0.8 mg/kg OTA groups. In conclusion, present study suggested that OTA induced pathological alterations were dependent upon dose and duration of exposure.

Key words: Broilers, Mycotoxins, Ochratoxin A, Ochratoxicosis, Pathology