Time Required to Develop Bone Fragility in Laying Hens

Two experiments were conducted to determine the length of time necessary to produce bone fragility in caged layers. Tibia ash and bone breaking strength of caged and floor pullets were found to be higher in floor pullets after four weeks, with a maximum difference between groups occurring at the end of eight weeks. Both groups exhibited a slight decrease in both tibia ash and bone breaking strength which was not statistically significant with each successive month of lay. It was further observed that tibia ash was closely associated with breaking strength, but was not as sensitive a measurement of bone fragility as was breaking strength.