Research Note: Current Methods Used in Determination and Evaluation of Tibia Strength: A Correlation Study Involving Birds Fed Various Levels of Cholecalciferol

Tibiae were removed from 300 75-wk-old laying hens for tibia strength analysis using two methods, direct photon absorptiometry and tibia breaking strength. Left tibiae with flesh intact were used for bone density determination with direct photon absorptiometry. Right tibiae were cleaned and dried for determination of tibia weight and tibia breaking strength. Partial correlation coefficients were estimated among bone density, tibia breaking strength, tibia weight, and body weight. A significant correlation was observed between tibia breaking strength and bone density measurements (r = .66, P less than or equal to .0001). Tibia weight and tibia breaking strength were also significantly correlated (r = .62, P less than or equal to .0001), as well as bone weight and bone density (r = .71, P less than or equal to .0001). Tibia weight and BW were also significantly correlated (r = .66, P less than or equal to .0001), necessitating covariance adjustment for BW. Bone densitometry measurements are less variable than tibia breaking strength measurements, and bone densitometry does not require cleaning bones of flesh before measurement.