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RESUMO -O objetivo deste trabalho foi avaliar o desempenho de bezerros de corte, do nascimento aos 12 meses de idade, filhos de vacas Charolês (C), Nelore (N), mestiças CN e NC, mantidas em pastagem nativa, suplementadas com farelo de arroz integral e que desmamaram aos 42 ou 63 dias pós-parto, ou não suplementadas e que desmamaram aos 63 dias. A idade das vacas variou de 3 a 12 anos, sendo agrupadas em quatro classes, primíparas, jovens, adultas e velhas. Bezerros desmamados aos 63 dias de idade, cujas vacas foram suplementadas, apresentaram maior ganho de peso médio diário (GMD) durante o aleitamento (561 contra 457 g), foram mais pesados ao desmame (67 contra 59,9 kg) e aos 84 dias (76 contra 69,2 kg) em relação aqueles cujas vacas não foram suplementadas, não diferindo destes nos pesos aos 5, 7 e 12 meses. Bezerros desmamados aos 42 dias apresentaram menor GMD nos primeiros 21 dias após o desmame (360 contra 482 g) e foram menos pesados aos 12 meses (174,4 contra 189,4 kg) em relação aos desmamados aos 63 dias. Bezerros mestiços filhos de vacas CN e NC foram mais pesados ao desmame que os puros, não diferindo dos C aos 12 meses. Bezerros N apresentaram peso similar aos C no desmame, mas foram mais leves e apresentaram condição corporal inferior do que os últimos aos 5, 7 e 12 meses. O peso e a condição corporal dos bezerros filhos de vacas primíparas foi inferior aos demais, no entanto, não diferiram destes aos 9 e 12 meses. Não se justifica a suplementação das vacas quando se considera o peso dos bezerros após os 5 meses. O desmame aos 42 dias de idade não é recomendado, pois resulta em menor peso aos 12 meses.Palavras-chave: Bos indicus, Bos taurus, cruzamento, estado corporal, desmame precoce, ganho de peso Performance of Beef Calves Produced by Cows Submitted to Different Feeding Managements, Weaned at 42 or 63 Days of AgeABSTRACT -The objective of this work was to evaluate the performance of beef calves, from birth to weaning, produced by Charolais (C), Nellore (N), CN and NC crossbred cows, kept on native pasture, supplemented with rice bran and weaned at 42 or 63 days postpartum, or non supplemented and weaned at 63 days. Cow age ranged from 3 to 12 years, being classified as: first calf, young, adult and old cows. Calves weaned at 63 days of age, whose cows were supplemented showed higher average daily weight gain (ADG) during lactation (561 vs. 457 g), were heavier at weaning (67 vs. 59.9 kg) and at 84 days (76 vs. 69,2 kg) in relation to those whose cows were not supplemented, and did not differ in weight from the last ones at 5, 7 and 12 months. Calves weaned at 42 days showed lower ADG during the first 21 days after weaning (360 vs. 482g) and were lighter at 12 months (174.4 vs. 189.4 kg) in relation to those weaned at 63 days. Crossbred calves produced by CN and NC crossbred cows were heavier at weaning then the straightbreds, not differing from the C calves at 12 months. Nellore calves were similar in weight to the C calves at weaning, but were lighter and displayed lower body condition score t...

Andropogon lateralis is a tall and highly plastic tussock-forming grass native from southern South America. It is a frequent component of Campos and Subtropical highland grasslands that often becomes dominant under lax grazing regimes. The aim of this work was to analyze the response of species diversity and forage production of a natural grassland dominated by A. lateralis to a wide range of grazing intensity. We hypothesized that species diversity and forage production would both peak at the intermediate canopy heights determined by grazing regimes of moderate intensity. A grazing experiment was conducted in a highland grassland with mesothermal humid climate at 922 masl (Atlantic Forest biome, Santa Catarina state, Brazil) that comprised 87 species from 20 families but had 50% of its standing biomass accounted by A. lateralis. Four pre-/post-grazing canopy heights—12/7, 20/12, 28/17, and 36/22 cm (measured on A. lateralis)—were arranged in a complete randomized block design with four replications, and intermittently stocked with beef heifers from October 2015 to October 2017. Andropogon lateralis cover decreased (from 75 to 50%), and species richness increased (15–25 species m−2) as canopy height decreased. Grazing intensity did not affect annual forage production (4.2 Mg DM ha−1). This natural grassland dominated by A. lateralis had a high capacity to adjust to grazing regimes of contrasting intensity, maintaining forage production stable over a wide range of canopy heights. However, to prevent losses in floristic diversity, such grassland should not be grazed at canopy heights higher than 28 cm.

RESUMO -Estudou-se o desempenho de bovinos machos não-castrados das raças Aberdeen Angus (AA) e Hereford (HE) em confinamento, submetidos a dois níveis de energia, em esquema fatorial 2 x 2, sendo o menor nível com 3,07 e o maior com 3,18 Mcal/kg de energia digestível (12 e 32% de concentrado na dieta, respectivamente). Foram utilizados oito animais da raça AA e oito HE, com idade inicial de nove meses e peso médio inicial de 220,31 kg, que permaneceram confinados até que o peso da carcaça atingiu o mínimo de 190 kg (estimativa). Os animais da raça AA apresentaram maior consumo de MS, em % PV (2,27 vs 2,10%) e em g/kg 0,75 (91,4 vs 86,4 g Feedlot Performance of Young Aberdeen Angus and Hereford Steers Fed with TwoEnergy Levels ABSTRACT -The feedlot performance of Aberdeen Angus (AA) and Hereford (HE) steers submitted to two energy levels, in a 2 x 2 factorial scheme, being the lower level of 3.07 (12% of concentrate in the diet) and the higher of 3.18 Mcal of digestible energy/ kg of DM (32% of concentrate in the diet), was evaluated. Eight steers of each breed were used, with nine months of age and average initial weight of 220.31 kg. The animals were confined until the estimated carcass weight reached 190 kg of average minimum weight. AA animals showed higher DM intake per 100 kg of live weight (2.27 vs 2.10%) and per unit of metabolic weight (91.4 vs 86.4 g). Animals fed with the higher energy level showed higher DM intakes per day (6.31vs 5.71kg), per 100kg of live weight (2.26 vs 2.11%), per unit of metabolic weight (92.28 vs 85.44g), of digestible energy (DE) (20.58 vs 18.13 Mcal/day) and crude protein (CP) (0.845 vs 0.759 kg/ day), beyond a higher daily weight gain (1.409 vs 1.250 kg). The animals that received the lower level showed higher intakes of neutral detergent fiber (NDF), kg/day (2.23 vs 2.07 kg) and of acid detergent fiber (ADF), kg/day (1.13 vs 1.01 kg). The DM/day, neutral detergent fiber and acid detergent fiber intakes showed a linear behavior for feedlot period, when the animals received the lower energy level, and a quadratic pattern when the animals received the higher energy level. For DM intake expressed as percentage of live weight and per unit of metabolic weight, a cubic behavior was observed, for feedlot period for the animals fed with the lower energy level, however, for the animals fed diet with the higher level of energy the behavior was quadratic. The digestible energy intake had a linear behavior in the lower energy level and a cubic behavior in the higher energy level, according to periods.

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