Occurrence: Worldwide. Species affected: All. Age affected: All.

Causes: Deficiency of vitamin D3 in the diet.

Effects: Vitamin D3 is needed for proper Ca and P metabolism and in the formation of normal skeleton. Signs are therefore similar to Ca and P deficiency. Soft brittle bones (rickets) and retarded growth occur in young birds, whilst cage layer fatigue is seen in mature birds.

Vitamin D3 is needed for proper metabolism of...