Ivan Dinev - Department of General and Clinical Pathology, Faculty of Veterinary Medicine,Trakia University, ۶۰۰۰ Stara Zagora, Bulgaria

The purpose of this study was to determine the incidence of rickets types in broiler chickens on the basis of gross and microscopic lesions in field clinical cases with regard to differential pathomorphological diagnosis.Clinical, serological, gross anatomy and histological investigations were carried out in broiler chickens with signs of rickets. The survey included 12 finisher broiler flocks (ten Ross 308 and two Cobb 500 flocks) from 4 different farms.Gross lesions in chickens from two of farms were indicative of hypophosphataemic rickets and the other two- of hypocalcaemic rickets types. Microscopic lesions correlated to macroscopic ones.The results of investigations showed that lesions resulting from calcium deficiency were very different from those occurring after phosphorus deficiency or calcium excess. It was suggested that macroscopic lesions in the proximal tibiotarsus could be used to distinguish field cases of Ca-deficiency and P-deficiency rickets in broiler chickens. The lesions in other leg parts (femur and tarsometatarsus) were not consistent with regard to differential diagnosis of rickets types due to the insufficient lesions in these bones

broiler chickens, rickets types, gross and microscopic lesions, differential pathomorphological diagnosis