López-Campos, Ó., Aalhus, J. L., Galbraith, J., Larsen, I. L., Juárez, M., Uttaro, B. and Robertson, W. M. 2014. The relation of carcass physiological maturity to meat quality in the Canadian Bison Grading System. Can. J. Anim. Sci. 94: 55-62. A total of 119 bull (n=62) and heifer (n=57) bison carcasses were selected to determine the effectiveness of youthful to intermediate physiological maturity [ossification at the 9th/10th/11th thoracic spinous processes (≤50%; 51-65%; 66-80%)] range to accurately classify bison carcasses with respect to quality. Carcasses were classified into three maturity groups according to ossification at the 9th/10th/11th thoracic spinous processes (=50%; 51-65%; 66-80%). Carcass, meat quality and sensory evaluation data were then collected. Bull carcasses were significantly (P<0.0001) heavier than heifers (308.0 vs. 228.6 kg), while heifers had higher (P<0.0001) marbling scores than bulls (368 vs. 289). For both genders, ossification group had little or no impact (P>0.05) on any of the meat quality traits. Gender had an impact on the shear force values for both fresh (P<0.0001) and frozen/thawed (P=0.0002) samples, with bulls having higher values than heifers. Panellists detected differences between heifers and bulls in initial tenderness (P<0.0001; 7.11 vs. 6.27), flavour intensity (P=0.005; 5.40 vs. 5.14), amount of connective tissue (P=0.0002; 7.64 vs. 7.18), and overall tenderness (P=0.003; 7.13 vs. 6.50). Only initial juiciness was significantly affected (P=0.02) by the ossification group (5.38, 5.64 and 5.76). A gender×ossification group interaction was also detected for flavour intensity (P=0.004) and off-flavour intensity (P=0.03), but the magnitudes of the differences were in the order of one-half panel unit or less, generally below the detection of most consumers. The range of physiological maturity studied had limited effects on meat quality and support the elimination of an intermediate physiological maturity grade (51-80% ossification) from the Canadian Bison Grading System.