Impact and control of Infectious Bronchitis in layers and breeders

Unlike most world areas of massive poultry exploitation, Infectious Bronchitis in New Zealand has not been a threat for broilers or younger birds in rearing. The nature of the local strain of Infectious Bronchitis virus (IBV) has not shown to be as virulent as the classic or variant strains that constantly ravage the poultry industry of North and Latin America, Europe and Asia. No mortality has been observed on experimental infection of chickens with recently-isolated IBV from New Zealand, and only mild changes on the respiratory histology were observed. In addition, the high standards locally achieved in the sanitation of facilities, biosecurity and animal welfare have maintained the level of infection and injury to a minimum. Therefore, in New Zealand vaccines against Infectious Bronchitis are not used on broilers, for even when the IB virus may be infecting a broiler shed, any respiratory symptoms may not have been relevant enough to alter the overall economic performance of the flock.