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The relation of carcass physiological maturity to meat quality in the Canadian Bison Grading System. Can. J. Anim. Sci. 94: 55Á62. A total of 119 bull (n 062) and heifer (n 057) bison carcasses were selected to determine the effectiveness of youthful to intermediate physiological maturity [ossification at the 9th/10th/11th thoracic spinous processes (550%; 51Á65%; 66Á80%)] 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 (550%; 51Á65%; 66Á80%). Carcass, meat quality and sensory evaluation data were then collected. Bull carcasses were significantly (PB0.0001) heavier than heifers (308.0 vs. 228.6 kg), while heifers had higher (PB0.0001) 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 (PB0.0001) and frozen/thawed (P00.0002) samples, with bulls having higher values than heifers. Panellists detected differences between heifers and bulls in initial tenderness (PB0.0001; 7.11 vs. 6.27), flavour intensity (P 00.005; 5.40 vs. 5.14), amount of connective tissue (P00.0002; 7.64 vs. 7.18), and overall tenderness (P00.003; 7.13 vs. 6.50). Only initial juiciness was significantly affected (P00.02) by the ossification group (5.38, 5.64 and 5.76). A gender )ossification group interaction was also detected for flavour intensity (P00.004) and off-flavour intensity (P00.03), 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 (51Á80% ossification) from the Canadian Bison Grading System. Lo´pez-Campos, Ó ., Aalhus, J. L., Galbraith, J., Larsen, I. L., Jua´rez, M., Uttaro, B. et Robertson, W. M. 2014. La relation entre la maturite´physiologique de la carcasse et la qualite´de la viande dans le syste`me de classement canadien du bison.Can. J. Anim. Sci. 94: 55Á62. Un total de 119 carcasses de bison, taureaux (n 062) et ge´nisses (n 057), ont e´te´se´lectionne´es pour de´terminer l'efficacite´de la gamme de maturite´(jeune a`interme´diaire) [ossification aux 9/10/11 ie`me apophyses e´pineuses thoraciques ( 550 %; 51Á65 %; 66Á80 %)] a`classer pre´cise´ment les carcasses de bison selon la qualite´. Les carcasses e´taient classe´es dans un de trois groupes de maturite´selon l'ossification aux 9/10/11 ie`me apophyses e´pineuses thoraciques (550 %; 51Á65 %; 66Á80 %). Il y a eu alors une collecte de donne´es sur la carcasse, la qualite´de la viande et les e´valuations sensorielles. Les carcasses de taureaux e´taient significativement (PB0,0001) plus lourdes que les carcasses de ge´nisses (308,0 c. 228,6 kg), tandis que les ge´nisses avaient des cotes de persillage plus e´leve´es (P B0,0001) que les ta...

López-Campos, Ó., Aalhus, J. L., Larsen, I. L., Juárez, M. and Basarab, J. A. 2014. Effects of production system and growth promotants on the physiological maturity scores in steers. Can. J. Anim. Sci. 94: 607–617. Over a 2-yr period, 224 crossbred steers were allotted to a 2×2×2 factorial arrangement of treatments to determine the effect of the production system (calf-fed vs. yearling-fed), growth implant strategy (non-implanted vs. implanted) and β-agonist supplementation (no ractopamine vs. ractopamine) on physiological indicators of maturity. Dentition and ossification scores along the vertebral column were collected post-mortem during head inspection and grading. Dentition score was significantly affected (P<0.001) by production system, but not by implant (P=0.68) or β-agonist (P=0.31). There were significant interactions (P<0.001) between production system and implant strategy on the frequencies of carcasses showing ossification in the thoracic, lumbar and sacral vertebral processes. There was a significant interaction (P<0.0001) between the production system and implant strategy on the frequencies of the carcasses considered as <21 or >21 mo of age based on a segregation model using only physiological maturity assessments. These data emphasize the inability of physiological scores to accurately reflect chronological age, with overall classification accuracies of 0.68 and 0.53 for dentition and ossification scores. The highest overall classification accuracies were obtained using the thoracic (0.74) or lumbar (0.69) ossification scores. Implants accelerate the ossification process, particularly in younger animals, thus having a dramatic effect on numbers of animals eligible to be categorized as <21 mo of age based on physiological maturity evaluation.