Comparative investigations of infectious runting and stunting syndrome in vaccinated breeder chicks by inactivated reovirus and chicks from non-vaccinated breeders.

Reoviruses are important pathogens responsible for poor growth performance and silent losses in the poultry industry. They are associated with many disease and syndromes such as malabsorption (runting and stunting syndrome), respiratory diseases and immunosuppression. Broiler birds are most susceptible to viral infections during the early post hatching period. Therefore, the transfer of maternal immunity to embryonated eggs is proved to be a primary means of protection from viral infections. In the present investigation, growth performance and pathology in breeder vaccinated and non-vaccinated chicks were studied after a challenge with the homologous malabsorption strain of the reovirus. Improvements in growth performance (mean live body weight, feed conversion ratio, broiler performance efficiency index, and protein efficiency index) in breeder vaccinated chicks were compared with non-vaccinated breeder chicks. The non vaccinated chicks showed various signs and lesions indicative of the reoviral malabsorption syndrome (MAS), whereas the vaccinated chicks showed very minimal alterations, demonstrating that the vaccination of breeders with homologous strains of the reovirus is profitable, and can help to increase the performance of broiler birds.