Comparison of bone quality in table egg layers by quantitative ultrasound, 3-point-bending test, and ash content

This study aimed to compare the performance of 2 quantitative ultrasound (QUS) devices and to investigate the possible relationship between bone density, measured by speed of sound (SOS), and the biomechanical properties of bone. The bone density of humerus and tarsometatarsus of 46, 29-week-old laying hens housed in conventional cages were measured with 2 QUS devices. After testing, the birds were humanely euthanized and their left tibiotarsus and tarsometatarsus were collected. The diameter of these bones was measured at mid-shaft. Bending moment and peak force were evaluated using a TA-HD Plus instrument. Statistical analysis was performed in JMP Pro 16. For all the analyses, significance was set at P< 0.05. There was poor agreement in the SOS results between both devices. There was a moderate positive linear correlation (r² > 0.6) between bending moment and peak force. No significant linear correlation was observed between the bone diameter and the bending moment or the peak force, or between SOS or bone ash content and any of the mechanical properties measured. A nominal logistic fit model was used to compare low vs normal bone density to the biomechanical properties. A bone was defined to have low density if its SOS was below 1 standard deviation from the mean. A model that linked all 3 biomechanical properties (P = 0.0173) was significantly correlated with the density (low vs normal) of tibiotarsi. Furthermore, the hen's tarsometatarsus with a higher bending moment and lower peak force had an increased odds ratio of low density tibiotarsi (P = 0.0293). This study failed to demonstrate a relation between the SOS and biomechanical properties of bone. While QUS was noninvasive assessment, the devices provided minimal or no association with the mechanical or ash content of the bones. Testing and validation of noninvasive tools are needed to expand our understanding of bone health and offer early detection of bone loss mass in layer flocks in longitudinal studies to develop effective management and intervention strategies.