Causes of sudden drop in egg production in New Zealand laying flocks

Summary

Ten cases of sudden drop in egg production were investigated. All outbreaks occurred between April and October. In 4 cases infectious bronchitis was diagnosed. One case each was attributed to infectious laryngotracheitis, avian monocytosis, fowl cholera, cage layer fatigue, and fatty liver haemorrhagic syndrome. One case remained undiagnosed.

The results indicate that infectious bronchitis is likely to be the most important single disease responsible for the sudden drop in egg production syndrome but that a variety of other infectious and metabolic disease may also be implicated.