In order to evaluate the influence of tropical grass sward structure on the intake of grazing cattle, five sward heights (60, 80, 100, 120, and 140 cm) of Panicum maximum Jacq. were established, in a completely randomized design with two replications. Four black-and-white coat Holstein heifers, carrying feces and urine bags, were used in grazing tests of 45 minutes each. Number of bites and feeding time were registered by counters and chronometers. Total herbage mass consumed was obtained by double sampling technique. Increasing sward height increased bite mass, followed by an increase in chewing number. The increase in the length of both expanded leaves and expanding leaves, resulted in individual bite per leaf, leading to an increase in biting time, and consequent linear decrease in bite rate. Since increases in time per bite was proportionally greater than that for bite mass, total herbage mass consumed and intake rate stabilized at the highest sward heights. Under these conditions, the physical limitation imposed by sward structure led to a lower efficiency of foraging by the animals, even at high forage allowance situation. Intake rate was maximized at pasture height of 109.3 cm.
bovine; bite mass; sward structure; tropical grass
