Carcass characteristics and non-carcass components of young ½ Purunã x ½ Canchim bulls fed rations with three concentrate contents

Improving the quality and energy content of rations increases performance in feedlot cattle, resulting in higher weight at slaughter, better carcass quality and a higher yield of non-carcass components. The purpose of this study was to evaluate the effect of increasing concentrate content in the ration on the carcass traits and weight of non-carcass components of young bulls finished in a feedlot. Eighteen young crossbred ½ Purunã x ½ Canchim bulls were used, with an average body weight (BW) of 278 kg and 12 months of age at the start of the experiment. The experimental design was completely randomized with three treatments and six replicates, where the treatments were the contents of 0.71, 0.97 and 1.24% BW day-1 of concentrate in the ration, on a dry matter (DM) basis. Corn silage was used as roughage and was provided ad libitum during the experiment. The young bulls were kept in the feedlot for 168 days and slaughtered at 17 months of age. There was a linear effect of concentrate content on the slaughter weight (SW) and hot carcass weight (HCW), which increased from 433 to 485 kg and from 248 to 280 kg between 0.71 and 1.24% BW in DM day-1 of concentrate. This represented an increase of 9.87 kg in SW and 6.16 kg in HCW for each 0.10% BW in DM day-1 of concentrate added to the ration. The hot carcass yield, rib eye area, subcutaneous fat thickness and the proportions of bone, muscle and fat in the carcass were not affected by the concentrate content and showed mean values of 57.3%, 79.6 cm2, 3.20 mm, 14.88%, 65.21% and 20.67%, respectively. There was a linear effect of concentrate content on the carcass temperature after cooling, which increased from 8.1 to 9.0 oC between 0.71 and 1.24% BW in DM day-1 of concentrate. An increase of 0.16 oC in the post-cooling carcass temperature for each 0.10% BW in DM day-1 of concentrate added to the ration was observed. The weight of internal organs and the perirenal and internal fat deposition were not affected by the concentrate content. The inclusion of 1.24% BW in DM day-1 of concentrate in the ration is recommended to obtain high SW and high HCW. Below this level, the carcass tissue composition and weight of non-carcass components are not modified.