Bone Pathology of Birds Affected with Cage Layer Fatigue

The term cage layer fatigue was used initially in North America (3), to describe a leg weakness in high-producing hens housed in cages. Since this report, cage layer fatigue has been described in other countries (1,5,6,10), but there have been few detailed descriptions of the bone pathology of affected birds under controlled conditions. Spontaneous occurrence of cage layer fatigue in experiments with birds fed two different phosphorus supplements (8,9) allowed a detailed study of affected birds on a well defined diet.