Comparative susceptibility of native chicken breeds of Bangladesh to experimental Eimeria tenella infection.

Eimeria tenella is the major protozoan parasite that causes coccidiosis in chickens, and its clinical and pathological response shows significant variations among breeds. This disease has a major economic impact on growers and the poultry industry worldwide. Very little information exists concerning the challenge infections of native chicken breeds of Bangladesh. The present study was undertaken to investigate and compare the pathology and clinical manifestations of experimental E. tenella infection among native (indigenous) chicken breeds of Bangladesh (Hilly, Naked Neck, and Deshi), in comparison to the susceptible exotic Sonali breed. In order to achieve this, a controlled experimental infection was carried out, and weight changes, Feed Conversion ratio (FCR), OPG counts, lesion severity, qPCR quantification of oocysts output, and dropping score were measured at 6, 10, and 14-Days post-infection (DPI). Distinct breed-specific differences in susceptibility were elicited. Sonali chickens exhibited the highest oocyst counts, reaching up to 103,200 at 14 DPI, along with significant weight loss and severe cecal pathology marked by diffuse hemorrhagic lesions. On the other hand, the indigenous breeds had low OPG counts as low as 100 in Hilly chickens, insignificant changes in weights, and mild pathological features characterized by reduced inflammation and hemorrhagic enteritis. This study highlights significant breed-specific differences in susceptibility to E. tenella, offering valuable insights into potential resistance or tolerance mechanisms. These findings support the use of native breeds in selective breeding programs aimed at improving disease resistance and underscore the importance of targeted control strategies for effective coccidiosis prevention and management.