ABSTRACT. This study aimed to evaluate the dynamics, population density of tillers and stability index of Urochloa brizantha in silvopastoral systems composed of babassu palm trees in the Pre-Amazon region. Four systems consisting of different densities of palm trees (80, 131, and 160 palms ha-1) and a monocrop were evaluated. The rates at which the basal tillers appeared in systems with 131 and 160 palms ha-1 were similar to each other and were slower compared to the monocrop pasture and the system with 80 palms ha-1. Despite the variations, the stability index was always higher than 1.0, which infers a compensatory mechanism between tiller appearance and mortality rate, since monocrop pastures and systems with 80 palms ha-1 have a higher rate of tissue turnover with high rates of tiller appearance and mortality; in contrast, the system with 160 palms ha-1 presents high tiller survival rates. Both the 160 and 131 palms ha-1 systems indicate impaired canopy renewal, as seen in the low appearance rate of basal tillers due to shading. As such, the tillering dynamics of the systems vary according to the density of palm trees, and the smaller tree densities favor the tiller turnover in the first generations evaluated.

RESUMO Objetivou-se com o presente trabalho avaliar a degradabilidade in situ da matéria seca (MS) e a composição químico-bromatológica dos componentes morfológicos folha e colmo da Urochloa brizantha cv. Marandu em sistemas silvipastoris compostos por palmeiras de babaçu (Attalea speciosa) e em monocultivo na região Pré-Amazônica Maranhense. Foi utilizado o delineamento inteiramente casualizado com 0, 80, 131, 160 palmeiras adultas.ha-1, caracterizando monocultura (Mono), baixa densidade de palmeiras (BDP), média densidade de palmeiras (MDP) e alta densidade de palmeiras (ADP) durante os períodos chuvoso e seco. Foram colhidas amostras representativas de cada um dos sistemas silvipastoris, utilizando quadrados de 0,25m2. Eles foram posicionados de forma aleatória em pontos representativos dos pastos no momento da amostragem e as plantas contidas no interior de cada quadrado foram cortadas a cada 28 dias, rente ao solo. As amostras, após pesadas, foram separadas em componentes morfológicos folhas e colmos, levadas a estufa e feitas as análise laboratoriais. O sombreamento proporcionado pelas palmeiras de babaçu influenciou o valor nutritivo do capim-Marandu em ambos os períodos de avaliação, principalmente no teor de proteína bruta nos sistemas silvipastoris, observou-se que a degradabilidade in situ da matéria seca das folhas foi maior que o colmo e que houve pouca influência dos sistemas pastoris nos parâmetros de degradabilidade.

SUMMARY The objective of the present work was to evaluate the in situ degradability of dry matter (DM) and the composition of components morphological leaf and stem of Urochloa brizantha cv. Marandu in silvopastoral systems composed of palms of babassu palm (Attalea speciosa) and monoculture systems in region Pre-Amazon Maranhense. The experimental design was completely randomized with 0, 80, 131, 160 adult palms.ha-1, characterizing monoculture (Mono), low density of palm trees (LDP), average density of palm trees (ADP) and high density of palm trees (HDP) during the periods rainy and dry. Representative samples were taken from each one of the systems silvipastoris, using squares of 0.25m2. They were positioned at random in representative points of pastures at the time of sampling and the plants contained inside of each square were cut every 28 days, flush to the ground. The samples, after heavy, morphological components were separated in leaves and culms, carried the oven and made the laboratory analysis. The shade provided by trees of babassu influenced the nutritive value of Marandu grass both evaluation periods, mainly in crude protein content in silvopastoral systems, it has been observed that the in situ degradability of dry matter of the leaves was greater than the stem and that there was little influence of grazing systems in parameters of degradability.