R. Bras. Zootec.01/Dec/2006;35(6):2253-9.
Displacement and forage searching patterns of Holstein heifers in mombaçagrass pasture
DOI: 10.1590/S1516-35982006000800008
To evaluate grazing strategies of cattle on pastures, four Holstein black and white coating heifers were submitted to five sward heights of mombaçagrass (Panicum maximum Jacq.) pasture, in a completely randomized design, with two replications, between February and April, 2002. The experimental animals were evaluated during 45 minutes tests. Number of bites, number of feeding stations, number of steps and feeding time were measured, using chronometers and counters. The number of feeding stations per minute decreased quadratically (Y= 16.3199 – 0.2424 x + 0.000996 x2, R2 = 0.9328, P = 0.0031), from low to tall sward, as a result of the greater available mass present in the highest sward heights, that reduced the searching for other feeding stations. The number of steps between feeding stations increased (Y= 0.7247 + 0.01603 x, R2 = 0.6172, P = 0.0043) increasing the exploration of pasture environment. With the increase in available forage dry matter, the animals reduced total number of steps (Y= 513.998287 – 2.659875 x, R2 = 0.728076, P = 0.0016), steps by minute (Y= 11.567445 – 0.058396 x, R2 = 0.724633, P = 0.0013) and, consequently, the intensity of area utilization (Y= 9.533139 – 0.051351 x, R2 = 0.7708, P = 0.0005), as the greater sward height assured high forage intake. The animals showed adaptive feeding strategies to different pasture structures, in an attempt to improve their ingestive efficiency.
Keywords: grazing behavior; Holstein heifers; crossbreed cows; pasture structure