A Comparative Analysis of the Conventional Versus Molecular Detec-tion of Salmonella spp. Infection, with Particular Emphasis on the His-topathologic Changes Observed in Layer Hens

This research was carried out to investigate the presence of Salmonella SPP in layer poultry farms through various microbiological tests . A total of 585 samples (from 150 suspected birds) included (liver (150), ceca (50), heart (48), spleen (37), oviduct (150), ovary (150) were obtained from flocks in Diyala. Determination of salmonella spp was carried out via PCR tech-nique, biochemical tests, serotyping by O antigen and H antigen, API 20 and Viteck. Liver samples were examined microscopically to detect any changes. The results revealed that the highest number of Salmonella spp. isolates was seen in liver (34) (25 Salmonella ohio, 4 Salmonella Kentucky and 5 Salmo-nella enteritidis). and the rate of infection reach to (22.66%) followed by ovary (15) (10%)(13 Salmonella ohio and 2 Salmonella enteritidis ), oviduct (6) (4%)( 5 Salmonella ohio and 1 Salmonella enteritidis). The histological examination of the liver showed necrosis of hepatocytes, hemorrhage, ag-gregation of inflammatory cells.In conclusion, S. ohio, S. enteritidis, and S.Kentucky were the main causative agent for Salmonellosis in laying hens at Diyala governorate .