The aim of this study was to evaluate the influence of genetic group, sex and level of protein-energy supplementation on the performance and carcass traitsultrasound prediction of weaned calves Nellore and crossbred animals ½ Nellore x ½ Aberdeen Angus. A completely randomized design in a factorial 2x2x2, were used, with two levels of protein-energy supplementation, two sex and two genetic groups. Fifty-six animals were used (28 Nellore and 28 crossbred ½ Nellore x ½ Aberdeen Angus), equally divided between males and females, maintained on grazing Brachiariabrizanthacv. Marandu and evaluated in three experimental periods: period 1 = protein-energy supplementation in the dry season; period 2 = protein-energy supplementation during the rainy season; period 3 = only mineral supplementation. In the dry season, they were supplemented with levels of 0.5 and 1% of body weight (BW) and in the rainy season with 0 and 1% BW. Dry matter intake (kg day -1 , % BW, g kgBW 0.75-1 ) was estimated. In vivo ultrasound measurements of carcass were: loin eye area (LEA), fat thickness (FT) and rump fat thickness (RFT). There was influence of genetic group and protein-energy supplementation levels on average daily gain (ADG) of animals in period 1 and 2 (P < 0.05). Sex affected the ADG only in period 2, and the males had 754 gday -1 and females, 582 g day -1 . There was no interaction of genetic group x sex x supplementation level. At the end of the experimental period (end of period 3), it was found that male animals and crossbred animals ½ Nellore x ½ Aberdeen Angus had higher ADG (716 and 748 g day -1 , respectively). The values of dry matter intake (DMI) were influenced by genetic group and sex, in all periods, verifying highest intake in crossbred animals ½ Nellore x ½ Aberdeen Angus, with better feed conversion for crossbred animals. Regarding ultrasound measurements taken on the carcass, the influence of sex on FT and RFT, it was observed, and the males showed higher values, 3.24
ResumoObjetivou-se neste estudo avaliar a influência do grupo genético, sexo e níveis de suplementação proteicoenergética sobre o desempenho e características de predição de carcaça de bezerros desmamados da raça Nelore e ½ Nelore x ½ Aberdeen Angus. Utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 2x2x2, sendo dois níveis de suplementação, dois sexos e dois grupos genéticos. Foram utilizados 56 animais (28 Nelore e 28 ½ Nelore x ½ Aberdeen Angus), divididos igualmente entre machos e fêmeas, mantidos em pastagem de Brachiariabrizantha cv. Marandu e avaliados em três períodos experimentais: período 1= suplementação proteico-energética na estação seca; período 2= suplementação proteico-energética na estação chuvosa; período 3= apenas suplementação mineral. Na estação seca, suplementou-se com níveis de 0,5 e 1% do peso corporal (PC) e na estação chuvosa 0 e 1% do peso corporal. Foram estimados o consumo de matéria seca (kg dia -1 , % PC, g kgPC 0,75-1). As mensurações ultrassonográficas de carcaça in vivo foram: área de o...