As vertebrates increase in body mass, during growth or across generations, the limb bones supporting their mass must also undergo changes to avoid fracture. Some vertebrates have seen large increases in body mass over relatively short evolutionary time scales, for example, meat producing animals and certain human populations. A recent study showed that heavier domestic turkeys have relatively shorter and more robust hind limb bones than their wild counterparts, however, it is unknown how the bone tissue itself might be changing in response to increased body mass. In this study we examined cortical bone mineral density in the humerus, femur and tibiotarsus as well as bone strength and distribution in the tibiotarsus. From ages 10 to 18 weeks, male turkeys were repeatedly CT scanned in vivo (n=100/line). We found that in line A, selected for reproductive traits, bone mineral density increased in all three bones measured as the birds grew (P<0.05). However in line B, with no selection for reproductive traits, bone density decreased as body mass increased (P<0.001). The polar moment of area in the tibiotarsus, a measure of bending strength, increased during growth in line A (P<0.0001) but was not significantly different from zero in Line B (P=0.2117). Interestingly forelimb and hind limb bones exhibited similar trends in bone density, even though the forelimbs presumably undergo very little loading in the largely flightless domestic turkeys. Calcium is mobilized from cortical bone during egg laying, which is likely why the reproductive selected line exhibits increased cortical bone density with growth, providing a secondary biomechanical advantage. Our future work will include females of these lines to further evaluate the factors influencing bone density.