Bone strength comparisons were made on tibiotarsi of chicks and poults fed various levels of dietary protein and either loaded or not loaded with artificial weights. Stress and modulus of elasticity were evaluated for their ability to measure strength and rigidity differences in bones while accounting for various bone size. Often comparisons between birds of different ages and body weights are attempted despite various bone size and dimension. These terms identified the weaker, less rigid bones in a comparison between chicks fed a low calcium, low phosphorus diet and a control group matched for age, weight, and bone size. Stress values were not significantly different when ad libitum-fed controls and restriction-fed controls were compared even though body weights were significantly different. This suggests that bone strength comparisons can be made on bones that differ in size. Artificial weight loading of chicks or poults had no consistent effect on stress or modulus of elasticity. This would suggest that this type of exercise had no influence on bone strength. Turkey poults fed 28% dietary protein appeared to have stronger bones than those fed lower protein levels; however, when bone size and dimension are accounted for, no differences in bone strength resulted from the feeding of various protein levels. These findings suggest that stress and modulus of elasticity are better terms to use than force in making bone strength comparisons between groups of birds which may differ in body size and bone dimension.