Desempenho e características de carcaça de bovinos de diferentes grupos genéticos abatidos com 16 ou 22 meses e com 422, 470 ou 520 kg de peso vivo

Abstract

The aim of this study was to evaluate the animal performance and the carcass characteristics of bulls from three different genetic group and ½ Purunã x ½ Canchim bulls with 16 or 22 months old finished in feedlot and slaughtered with three different weights (422, 470 or 520 kg of live weight). The experiment was carried out at cattle sector of Experimental Station of Model Farm from Agronomic Institute of Paraná in Ponta Grossa. 65 bulls were separated in three genetic groups: 1. Canchim - CAN (16 bulls); 2. ½ Purunã x ½ Canchim - PCA (36 bulls) and 3. ¾ Purunã x ¼ Canchim - PUC (13 bulls) and 113 bulls ½ Purunã x ½ Canchim separated according to the finishing system (super precocious - 16 months or precocious - 22 months) and to the slaughter weight (light - 422 kg; medium - 470 kg and heavy - 550 kg). For the super precocious system, 22 bulls were slaughtered with light final live weight (FLW), 20 bulls with medium FLW and 20 bulls with heavy FLW. For the precocious system, 18 bulls were slaughtered with lightFLW, 16 bulls with mediumFLW and 17 bulls with heavy FLW. The bulls were fed with a diet containing 12% of crude protein and 72% of total digestible nutrients. The roughage was corn silage. The concentrate were composed by 25% of soybean meal, 73% of cracked corn and 2% of mineral salt. The proportion of roughage:concentrate was 52:48. The rations formulation and the quantity given to the bulls was to achieve 1.20 kg of gain daily. The initial live weight in feedlot was lower (P<0.05) to CAN genetic group (200.56 + 6.97 kg) and higher to PCA (271.33 + 4.64 kg) and to PUC (256.62 + 7.74 kg) genetic groups; there was no difference between PCA and PUC genetic groups. In the same way, the final weight was lower to CAN (437.38 + 8.86 kg) in comparison with PCA (459.22 + 5.91 kg) and PUC (466.77 + 9.83 kg). The average daily gain was higher (P<0.05) to PUC (1.47 + 0.07 kg) in comparison with CAN (1.17 + 0.06 kg) and PCA (1.24 + 0.04 kg); there was no difference (P>0.05) between CAN and PCA genetic groups. The hot carcass dressing was higher (P<0.05) to CAN (58.41%) genetic group in comparison with PCA (53.55%) and PUC (52.91%) genetic groups. There was not interaction (P>0.05) between the finishing system and the slaughter weight. The bulls slaughtered with medium (1.47 kg) and heavy weight (1.43 kg) presented higher (P<0.05) average daily gain in comparison with bulls slaughtered with light weight. The dry matter intake and the feed conversion are higher (P<0.05) to heavy bulls. The bulls from super precocious finishing system present better performance than bulls from precocious finishing system. Younger bulls present higher hot carcass dressing and higher hot carcass weight.