Associations among computed tomographic measures of bone and muscle quality and biomechanical measures of tibiotarsal bone quality in laying hens.

Objective: The objectives of the current study were to quantify laying hen sternal carina (keel) and tibiotarsal bone and muscle quality using clinical CT, tissue level, and biomechanical measures; test associations among muscle transverse sectional area, bone mineral density, and biomechanical measures of bone quality; and determine whether CT measures of bone and muscle quality would be predictive of biomechanical measures of tibiotarsal bone quality.

Animals: 60 40-week-old Hy-Line brown laying hens were used.

Methods: Associations among CT imaging, tissue level, and biomechanical measures of tibiotarsal and keel bone and muscle quality were tested using multivariate correlational analyses. Bivariate and generalized regressions were performed to determine whether CT measures were predictive of biomechanical measures of tibiotarsal bone quality.

Results: Low positive correlations were identified between tibiotarsal muscle transverse-sectional area (cross-sectional area [CSA]) and bone mineral density (BMD) in the proximal location of the bone (r = -0.11 to 0.31). Tibiotarsal muscle CSA was also low to moderately correlated with biomechanical measures of bone quality (r = 0.20 to 0.41). Keel muscle CSA values were not correlated with keel BMD values, but they were correlated with biomechanical measures of tibiotarsal bone quality (r = 0.18 to 0.40). Keel CT measures of bone quality were not correlated with tibiotarsal CT measures of bone quality. At the proximal location, muscle CSA and tibiotarsal BMD were predictive of biomechanical failure load (F = 9.68, P = .0003muscle CSA; F = 9.13, P = .004tibiotarsal BMD).

Clinical Relevance: Findings supported using noninvasive CT measures of muscle and bone quality in longitudinal research studies evaluating the effects of interventions on laying hen welfare.