Avian coccidiosis, Commercial broiler farms, Coccidiostats, Dinajpur district
Experimental chickens: A total of 234 diseased and dead birds were examined from 50 farms in the small scale commercial broiler farms at different regions of Dinajpur district in Bangladesh. Among the examined bids, only 20 were found to be positive for coccidiosis. A detail flock history in relation to the incidence of diseases including housing, location of farms, source of birds, age, population of the birds per flock, rearing system, litter material, feeding and watering system, biosecurity, previous history on coccidia outbreaks, intervals between the batches, rearing of one more batches in the same farm at the same time etc., were also recorded. The birds affected with coccidiosis were submitted to the pathology laboratory for the diagnosis and treatment and other processing. Clinical examination of affected birds:The general health condition and age of the chicken were recorded. The clinical signs were recorded during the physical visit of the affected flocks and the farmer’s complaints about the affected birds were also considered. Necropsy findings of suspected birds: The necropsy was done on the suspected dead and diseased birds taken from different upazilla of Dinajpur district. At necropsy, gross morbid changes were observed and recorded carefully by systemic dissection. The collected samples were preserved at 10% formalin for the histopathological study. Gross morbid lesions of different organs were registered during the course of necropsy of the birds. Histopathological examination: During necropsy, various organs having gross lesions were collected, preserved at 10% formalin, processed for the histopathological study. Formalin fixed samples of the small intestine, large intestine and caeca from the diseased and dead chicken were processed for paraffin embedding, sectioning and staining with haematoxylin and eosin according to standard method (Luna, 1968) for histopathological study. Examination of faeces: Faecal samples were collected directly from the affected flocks. Interstinal content was collected during the postmortem examination of the birds. The slides were examined under microscope for detection oocysts in low and high magnification. Photography: All images related to the present study were taken directly from microscope using different objectives manipulation of zooming system of a digital camera (Canon, 1XY, 16.1 Mega pixels, Japan). The images were provided following minute modification for the better illustration of the study.