Mycotoxins are among the most important environmental contaminants. In the present study, ochratoxin A (OTA) was produced by propagation of Aspergillus ochraceus and fed to breeder hens. For this purpose, 84 breeder hens were divided into seven groups (A-G). Group A served as control, while groups B, C, D, E, F and G were fed OTA at 0.1, 0.5, 1.0, 3.0, 5.0 and 10.0 mg/Kg feed, respectively for 3 weeks. Clinical signs, feed intake, feed conversion ratio and egg mass production were recorded on daily basis, while body weight was recorded on weekly basis. Lesions on visceral organs and serum biochemical parameters were determined. Significant decrease in feed intake, body weight and egg mass production was found in the OTA treated groups compared to control (P<0.05). Among different groups, diarrhea, unthriftiness, water intake and depression increased with increase in dietary OTA levels. Enlargement and hemorrhages on liver and kidney were more severe in birds fed higher dietary OTA levels. Serum ALT, urea, creatinine and total protein levels were significantly higher in OTA treated groups. It was concluded that production performance, pathological alterations and serum biochemical changes determined became more severe with increase in dietary levels of OTA.

Key words: Histopathology, Layer breeder, Ochratoxin A, Ochratoxicosis, Pathology, White Leghorn