A three-year-long field experiment was conducted in a continuous grazing system with a variable stocking rate to evaluate effects of increasing nitrogen levels in Marandu grass (Brachiaria brizantha Hochst ex A. Rich Stapf “marandu”) on herbage mass, forage accumulation rate (FAR), forage quality, stocking rate (SR), average daily gain (ADG), gain per hectare (GPH), and gain per kg of applied N. The experimental design was completely randomized with four treatments (control without application of N, and 90, 180, and 270 kg N ha⁻¹ year⁻¹) and three replicates (paddocks per treatment); nitrogen was applied in the form of urea. Herbage mass, crude protein (CP), FAR, SR, GPH, and the nitrogen nutrition index increased with increasing nitrogen level (P < 0.05), whereas the neutral detergent fibre (NDF), acid detergent fibre, and nitrogen usage efficiency decreased with increasing nitrogen level (P < 0.01). Crude protein was higher than 12% and NDF lower than 60% in all treatments. Nitrogen application rate affected ADG (P < 0.05) but did not fit any equation. The highest ADG was 90 kg N ha⁻¹ year⁻¹ (985 g animal⁻¹ day⁻¹). Increasing the nitrogen level is a promising way to improve Marandu grass production, nutritive value, and animal production.

Intensification of tropical grassland can be a strategy to increase beef production, but methods for achieving this should maintain or reduce its environmental impact and should not compromise future food-producing capacity. The objective of this review was to discuss the aspects of grassland management, animal supplementation, the environment, and the socioeconomics of grassland intensification. Reducing environmental impact in the form of, for example, greenhouse gas (GHG) emissions is particularly important in Brazil, which is the second-largest beef producer in the world. Most Brazilian pastures, however, are degraded, representing a considerable opportunity for the mitigation and increase of beef-cattle production, and consequently increasing global protein supply. Moreover, in Brazil, forage production is necessary for seasonal feeding strategies that maintain animal performance during periods of forage scarcity. There are many options to achieve this objective that can be adopted alone or in association. These options include improving grassland management, pasture fertilization, and animal supplementation. Improving grazing management has the potential to mitigate GHG emissions through the reduction of the intensity of CO₂ emissions, as well as the preservation of natural areas by reducing the need for expanding pastureland. Limitations to farmers adopting intensification strategies include cultural aspects and the lack of financial resources and technical assistance.

O manejo do pastejo permite que sistema com base na utilização de pastagem propicie altos rendimentos por animal e por área. Para isto, devem-se utilizar critérios de manejo com intuito de controlar, simultaneamente a qualidade e a quantidade de forragem e manter a sustentabilidade do sistema. A intensidade de pastejo é dinâmica, jamais permanece a mesma, mudando com a taxa de consumo pelos animais e também pelo crescimento das plantas, variando de hora a hora e dia a dia, por isso deve ser controla sistematicamente. Neste cenário, o consumo de forragem parece ser o fator que mais explica as variações no desempenho animal em relação a qualidade da forragem. A suplementação da dieta dos animais em pastejo com concentrado permite aumentar o desempenho de animais, reduzindo a idade de abate ou a da primeira cria. Contudo, as características nutricionais do suplemento devem variar em função da quantidade e da qualidade da forragem ofertada. Ao suplementar a dieta dos animais em pastejo com energia e proteína, pode-se manejar pastos mais baixos em relação a suplementação apenas com sal mineral, sem que ocorra redução da densidade populacional de perfilhos. Estas estratégias de manejo podem reduzir a probabilidade de degradação do pasto. Desta forma, a suplementação da dieta de animais permite aumento na capacidade suporte do pasto.

A 7 year experiment (2008–2014) evaluated cattle grazing intensity (sward height) effects on herbage mass, forage quality, and greenhouse gas emissions in continuously stocked pastures containing the tropical ‘Marandu’ palisade grass (Brachiaria brizantha (Hochst. ex A. Rich) Stapf cv. Marandu). The experiment consisted of three sward height treatments (15, 25, and 35 cm) and six replicates. There were four periods each year during the rearing phase. Significant effects were found for herbage mass, proportions of leaf and stem, crude protein, neutral detergent fiber, acid detergent fiber, lignin, animal performance, enteric methane (CH₄), and greenhouse gas (GHG) emissions from soils. When the canopy height increased from 15 to 35 cm, the herbage mass rose from 5.23 to 9.86 kg t ha⁻¹, leaf percentage decreased, and stem percentage increased. Crude protein content averaged 14.2%, and neutral detergent fiber averaged 58%. Average daily gain averaged 0.67, 0.81, and 0.90 kg ⁻¹ head⁻¹, while live weight gain ha^–1 was 649, 530, and 439 kg for the 15, 25, and 35 cm treatments, respectively. The weather variables explained the GHG emissions, interannual herbage mass, and structure variations.