Abstract   

    This study indicates that 1BV infection of laying chickens is of high economical importance as it adversely affects their production potentials. 18V-infected hens lay eggs of inferior quality compared to the uninfected hens. There were significant differences in the daily egg production, egg weight, shell weight and in the internal quality of eggs laid by the 18V infected and uninfected hens. The 1BV infection of developing embryos resulted into mortality, kidney lesions, stunting and curling and low hatchability compared to uninfected embryos. These effects were more severe on the SPF embryos than the embryos from the broiler breeder hens. 

Key words: Infectious bronchitis virus, layers, breeders, losses.