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Objetivou-se avaliar o desempenho produtivo, a eficiência econômica e a taxa de ingestão do suplemento em novilhos mestiços em pastejo no período da seca. Foram utilizados 20 novilhos Holandês × Zebu, não-castrados, com 19 meses de idade e peso médio inicial de 315,0 kg distribuídos em quatro piquetes de Brachiaria decumbens com 3,0 ha cada. Cada animal recebeu 4,0 kg/dia de suplemento, constituído de milho moído, farelo de algodão, mistura mineral e ureia/sulfato de amônia em quatro níveis: 0; 1,2; 2,4 ou 3,6% na matéria natural. O peso final e o ganho médio diário apresentaram comportamento quadrático, com respostas máximas estimadas obtidas para os níveis de ureia de 1,67% (399,9 kg) e 1,60% (0,956 kg/dia), respectivamente. O peso de carcaça quente, o rendimento de carcaça, as proporções de tecidos muscular, adiposo, ósseo e a relação músculo:osso na carcaça não foram influenciados pelos níveis de ureia. À medida que se elevou o nível de ureia, houve maior tempo para o suplemento ser totalmente consumido. A avaliação econômica dos suplementos, de forma diferencial ao tratamento sem ureia, comprovou maior eficiência econômica no nível de 2,4% de ureia. The objective was to evaluate productive efficiency, economic performance and supplement intake rate in crossbred steers on pasture during the dry season. Twenty 19-month-old Holstein × Zebu steers with 315±25 kg of live weight were alocated into four paddocks of Brachiaria decumbens with 3.0 ha each. Each animal received 4.0 kg/day of supplement based on ground corn grain, cottonseed meal, mineral mixture and urea/ammonium sulfate in four levels (0, 1.2, 2.4 and 3.6%) as fed basis. Final live weight and average daily gain presents quadratic behavior. Maximum responses estimated were observed at levels 1.67% (399.9 kg) and 1,60% (0.956 kg/day) urea, respectively. Hot carcass weight, carcass yield, the proportions of muscular, fat and bone tissues and the muscle:bone in the carcass ratio were not influenced by the levels of urea in the supplements. The economical evaluation of the supplements, unlike the treament without urea, showed greater economic efficiency for supplement containing 2,4% of urea. As urea levels were increased, more time was observed for total consumption of the supplements.

The objective was to study the effect of including different levels of glycerin on animal performance, feed efficiency, digestibility and ingestive behavior of Heifers on Brachiaria brizantha cv Marandu. The experimental period was 102 days, being the first 14 days as an adaptation period of heifers to experimental diets and management. There were used 36 crossbred heifers with an average initial weight of 226 kg and 13 months old, distributed in a completely randomized design with four treatments and nine replications: G0.0 = control, G2.80 = 2.80%, G6.10 = 6.10 and G9.00 = 9.00% of glycerin in dry matter of the ingest diet. The crude glycerin had 16% methanol and for its elimination it was heated to 75 °C before mixing the concentrate. Heifers were weighed every 28 days for evaluation of average daily gain (ADG). The dry matter intake was estimated from fecal output, recorded with the aid of chromic oxide (Cr2O3) as an external marker and indigestible dry matter (DMi) as an internal marker. Apparent digestibility was estimated from fecal output determined by chromic oxide. Feeding behavior was conducted by monitoring the activities of the animals by means of continuous observations with annotations by 24 hours at every five minutes, the average number of chews per bolus rumen, the time spent ruminating each bolus and the number of bolus ruminated over the period was recorded using digital stopwatches being nine values per animal. The inclusion of glycerin in the diet of heifers determined a reduction (P 0.05) among treatments. The intake of ether extract increased linearly (P 0.05) on the digestibility of dry matter, organic matter, neutral detergent fiber, protein, fat, carbohydrates and non-fibrous carbohydrates. Moreover, the inclusion of glycerin in the diets increased linearly (P 0.05) the number of periods in grazing and rumination. However, the number of idle period showed a quadratic equation (P 0.05) by the time period of grazing and rumination. The time of idle periods increased (P 0,05) entre os tratamentos. A ingestão de extrato etéreo aumentou de forma linear (P0,05) sobre os coeficientes de digestibilidade da matéria seca, matéria orgânica, fibra em detergente neutro, proteína bruta, extrato etéreo, carboidratos não fibrosos e carboidratos totais. Por outro lado, a inclusão de glicerina às dietas aumentou de forma linear (P0,05) o número de período em pastejo e ruminação. No entanto, o número de período em ócio mostrou uma equação quadrática (P0,05) o tempo por período de pastejo e ruminação. O tempo de período de ócio aumentou (P

O experimento foi conduzido para avaliar quatro fontes de fósforo para bovinos em pastagem de grama-estrela roxa (Cynodon nlemfuensis Vanderyst) e compará-las considerando o desempenho ponderal e os parâmetros fisiológicos. O delineamento experimental foi o inteiramente casualizado, utilizando 32 animais mestiços (zebuíno x taurino), com peso inicial médio de 347 kg, distribuídos ao acaso em quatro grupos, cada um recebendo suplemento mineral formulado com fosfato bicálcico, superfosfato triplo, fosfato monoamônio e fosfato de rocha de Araxá. O ganho de peso por hectare diferiu entre as datas de avaliação e teve redução significativa no último período, mas não entre as fontes de fósforo. O ganho médio diário não diferiu entre as fontes de fósforo e foi de 0,67; 0,65; 0,63 e 0,56 kg/dia, respectivamente, para fosfato bicálcico, superfosfato triplo, fosfato monoamônio e fosfato de rocha Araxá. As concentrações de osteocalcina mantiveram-se em níveis baixos (47,67 ng/mL) e foram semelhantes entre as fontes de fósforo. As fontes de fósforo foram eficientes em manter níveis adequados de fósforo no soro, com média de 7,03 mg/100 mL. This study aimed to evaluate four sources of phosphorus for cattle grazing African Bermudagrass (Cynodon nlemfuesis Vanderyst) pasture and to compare them considering weight performance and physiological parameters. It was used a complete random experimental design, with 32 crossbred steers (Bos indicus x Bos Taurus) at average initial weight of 347 kg randomly distributed in four groups, each one receiving mineral supplement formulated with dicalcium phosphate, supertriple phosphate, monoammonium phosphate or Araxá rock phosphate, as sources of phosphorus. Weight gain per hectare differed among evaluation dates and it was significantly reduced in the last period, but it did not differ among sources of phosphorus. Average daily gain did not differ among sources of phosphorus and it was 0.67; 0.65; 0.63 and 0.56 kg/day, respectively for dicalcium phosphate, supertriple phosphate, monoammonium phosphate and Araxá rock phosphate. Concentrations of osteocalcin were kept in low levels (47.67 ng/mL) and they were similar among sources of phosphorus. Sources of phosphorus were efficient in keeping appropriate levels of phosphorus in serum, with an average of 7.03 mg/100 mL.