Bovine metacarpal and metatarsal dimensions: Comparison of aberdeen—Angus and charolais steers slaughtered at three percentages of mature cow weight

Fifty-six Aberdeen—Angus (Angus) and 56 Charolais steers were used in a 2 (diet energy levels) × 4 (slaughter weights) × 2 (breeds) factorial experiment. Live slaughter weight groups within each breed were initial, 86 (light), 100 (middle) or 114% (heavy) of average mature cow weight (Angus dams, 467 kg; Charolais dams, 612 kg). Therefore, Angus were slaughtered at 408, 476 or 544 kg and Charolais at 526, 612 or 699 kg. Live, carcass and metacarpal and metatarsal traits were obtained. There were no important effects of diet (2.72 vs. 2.96 Meal metabolizable energy/kg of dry matter). Breed affected (P < 0.01) live body measurements in each slaughter weight group except in initial groups. Within initial groups, breed affected (P < 0.01) live fore- and rear-cannon lengths and wither height. Mean limb-bone weight, expressed as a percentage of live weight, was greater for Charolais than for Angus in each weight group. Bone length increases ceased within Angus between initial- and light-weight slaughter endpoints, but ceased in Charolais between light and heavy groups. Bone area and circumference increased through most weight increments for both breeds, confirming that appositional bone growth continues after length increases cease. Bone specific gravity was maximized in the middle-weight Angus, but increased (P < 0.01) between middle and heavy Charolais. Generally, these results indicate that bone growth subsides earlier and ossification is more advanced in Angus than in Charolais if both breeds are slaughtered at the same percentages of mature weight.