Biomass flow characteristics and forage accumulation were evaluated in Bermudagrass (Tifton 85) pasture managed under intermittent stocking with different management strategies. The management levels utilized were conventional (10 cm residual height and unfertilized), light (20 cm residual height and unfertilized), moderate (20 cm residual height with fertilization of 300 kg N/ha.year) and intensive (10 cm residual height with fertilization of 600 kg N/ha.year). A randomized design was used with repeated measurements over time, in two periods of the year, with four replicates. There was significant effect of management × period of the year on the leaf elongation rate (LER). The management levels under fertilization (0.59 and 0.60 cm/tiller.day for the intensive and moderate management, respectively) and the rainy season (0.49 cm/tiller.day) showed the greatest stem elongation rate. Leaf senescence rate (LSR) before and after and total LSR were modified by the management × period of the year interaction. The intensive management, with 0.38 leaves/tiller.day, as well as the dry period, with 0.27 leaves/tiller.day, showed higher leaf appearance rate. The lowest phyllochron was observed in intensive management and dry periods, as well as an interaction with the management of the same periods of the year. There was management × period of year interaction effect on leaf lifespan; the highest value was found under conventional management and dry period. Both production and forage accumulation rates were higher in the intensive and moderate management levels and dry season, and there was interaction of the intensive management system with the seasons. Managing pastures under moderate and intensive rotational stocking, which occurred mainly in the rainy and dry seasons, respectively, maximizes the flow of tissues and consequently production and accumulation of forage.

Foram avaliadas as características da biomassa do capim-tanzânia sob três frequências de desfolhação (85, 95 e 97% da interceptação da radiação fotossinteticamente ativa - IRFA) e dois resíduos pós-pastejo (índices de área foliar residual de 1,0 e 1,8) em delineamento inteiramente casualizado em arranjo fatorial 3 × 2, com quatro repetições. O maior período de descanso foi verificado para o menor resíduo pós-pastejo e a frequência com 97% de IRFA. Observou-se uma altura elevada, assim como maior IAF para a frequência com 97% de IRFA. Já no caso da densidade populacional de perfilhos (DPP) e no nº de folhas/perfilho, ocorreu uma interação entre os fatores, com uma redução nos seus valores nos pastos manejados com IAF residual de 1,8. As massas de forragem, com exceção da forragem morta, foram fortemente influenciadas pela frequência de desfolhação, mostrando maior produção para frequência de desfolhação com 95% de IRFA. A interceptação luminosa no residual, assim como a altura nessa condição, foram maiores para o maior resíduo pós-pastejo. A DPP residual apresentou interação entre os fatores com redução no perfilhamento nas freqüências 85 e 95% de IRFA no IAFr de 1,8. Na condição residual as massas de forragem foram fortemente influenciadas pelo IAF residual, com maior material remanescente do pastejo observado para o IAFr de 1,8. O uso de uma pastagem de capim-tanzânia não deve exceder 95% da interceptação da radiação fotossinteticamente ativa, mas é possível adotar resíduo pós-pastejo com índice área foliar residual 1,0.

It was evaluated the characteristics of the biomass of Tanzania grass under three defoliation frequencies (85, 95 and 97% interception of the photosynthetically active radiation - IPAR) and two post-grazing residue (residual leaf area index of 1.0 and 1.8) in a complete randomized design in a 3 × 2 factorial scheme with four replications. The longest resting period was observed for the lowest post-grazing residue and frequency of 97% of IPAR. A high height as well as a higher leaf area index for the frequency with 97% of IPAR was observed. However, for tiller population density (TPD) and the number of leaves/tiller, an interaction among factors occured, reducing their values on pastures managed with residual leaf area index of 1.8. Forage mass, except for dead forage, was strongly influenced by defoliation frequency, showing a higher production for defoliation frequency with 95% of IPAR. Light interception in the residue and height for this condition were higher for the highest post-grazing residue. Residual TPD showed interaction among factors with tillering reduction in the frequencies 85 and 95% of the IPAR of 1.8. In the residual condition, forage mass was strongly influenced by residual leaf area index, with more grazing remaining material observed for rLAI of 1.8. The use of Tanzania grass pasture cannot exceed 95% interception of the photosynthetically active radiation, but it is possible to adopt post-grazing residual leaf area index of 1.0.

Objetivou-se avaliar a composição químico-bromatológica, a digestibilidade e a degradação in situ da matéria seca da dieta consumida por ovinos em pastagem de Panicum maximum cv. tanzânia sob três frequências de desfolhação, determinadas pela interceptação da radiação fotossinteticamente ativa (IRFA) de 85, 95 e 97% no 1º e 4º dias de pastejo. O delineamento experimental foi inteiramente casualizado com arranjo fatorial 3 × 2 (três frequências de desfolhação e dois dias de pastejo), com quatro repetições (piquetes) por tratamento. Para determinação da composição químico-bromatológica e da digestibilidade e ensaio de cinética de degradação da matéria seca da dieta, foi realizada uma simulação de pastejo no 1º e 4º dias de ocupação. A diminuição da frequência de desfolhação piorou a composição químico-bromatológica, a digestibilidade e a degradação do capim-tanzânia. Recomenda-se frequência de desfolhação no capim-tanzânia menor ou igual a 95% de interceptação da radiação fotossinteticamente ativa visando à manutenção da qualidade do pasto.

The objective of this study was to evaluate the chemical composition, digestibility and in situ degradation of dry matter of the diet consumed by sheep grazing on Panicum maximum cv. Tanzania under three defoliation frequencies, determined by the interception of the photosynthetically active radiation in the canopy (PAR) of 85, 95 and 97% on the first and fourth days of the grazing period. A randomized complete design in a 3 × 2 factorial arrangement (three defoliation frequencies and two days grazing), with four replications (poles). To determine the chemical composition, digestibility and an in situ dry matter degradation trial, a grazing simulation was carried out on the 1st and 4th days. Reduced defoliation frequency decreased the chemical composition, digestibility and in situ degradation of the diet. Thus defoliation frequency of tanzania grass is recommended of less or equal to 95% photosynthetically active radiation to maintain pasture quality.