Morphogenetic components and accumulation in mulato grass at different frequencies and intensities of grazing

Grasses are the main feed source for ruminant livestock in tropical regions. Forage yield and quality are therefore extremely important for mitigating low productivity. Most studies of forage are based on dry matter production and nutritional value, and ignore grass morphogenetic and structural traits in the resprouting dynamic. Brachiaria hibrido cv. mulato was studied at 14, 21 and 28 d grazing frequencies, and 9-11 and 13-15 cm residual heights using a random block design and a 3 x 2 factorial arrangement with three replicates. Five variables were measured: forage accumulation; population stem density; stem appearance rate; stem death rate; and leaf tissue turnover. At all three frequencies, forage accumulation was highest under light grazing during the rainy season (2,769 kg dry matter at 14 d; 4,985 kg at 21 d; and 7,033 kg at 28 d). Under severe grazing in the first cycle, stem appearance rate was higher than under light grazing by 13 % in the northwinds season, by 8 % in the dry season and by 14 % in the rainy season. Leaf elongation was greatest at the 28 d frequency during the rainy season. Mulato grass exhibited the highest forage accumulation during the rainy season when harvested at a 28 d frequency under light grazing. Leaf elongation rate and leaf senescence exhibited the highest values when grazed lightly every 28 d at a low stem density.