Carcass characteristics of cull cows from different genetic groups feedlot finished and slaughtered with distinct weights

The objective of the experiment was to evaluate the carcass characteristics of crossbred cull cows, from the second (G2- 3/4Charolais (C) Nellore (N) and 3/4NC) and third (G3 - 5/8CN and 5/8NC) generations of Charolais - Nellore rotational crossbreeding, feedlot finished and slaughtered with 465, 507 and 566 kg. At the beginning of the experiment the average age, weight and body condition were, respectively, 8.5 years, 388.6 kg and 2.35 points. The diet, with 48:52 roughage: concentrate ratio, contained 12.5% crude protein and 2.99 Meal of digestible energy per kg of dry matter. Cows slaughtered with 566 kg produced heavier carcasses (318.5 kg), higher dressing percentage (56.24%) and subcutaneous fat thickness (7.54 mm) than cows slaughtered with 465 kg (245.0 kg, 52.71 and 4.72 mm, respectively) or 507 kg (264.6 kg, 52.12% and 4.4 mm, respectively). The increase of slaughter weight (465, 507 and 566 kg) did not alter the sawcut percentage (51.17, 50.64 and 50.63%), reduced the forequarter (36.93, 37.26 and 35.23%) and increased the sidecut percentage (11.9, 12.09 and 14.14%), respectively. For the measurements related to the carcass muscular expression, conformation was improved by slaughter weight increase (8.13, 9.47 and 10.9 points), respectively. Cushion thickness increased significantly when slaughter weight raised from 465 to 507 kg and Lougissimus dorsi muscle area increased only in cows with the highest slaughter weight. The 3/4CN cows showed higher sidecut and lower forequarter percentages in relative to 3/4NC cows.