Forage accumulation in brachiaria grass under continuous grazing with single or variable height during the seasons of the year

Abstract

The objective of this study was to evaluate grazing management strategies of Brachiaria decumbens cv. Basilisk managed with different heights under continuous grazing with cattle. Two grazing management strategies were evaluated: maintenance of pasture with an average height of 25cm throughout the experimental period and maintenance of pasture on the average of 15cm in height during winter, up to 25cm from the beginning of spring. The split-plot scheme and the randomized block design with four replications were adopted. The grazing management strategies corresponded to the primary factor, while the seasons (winter, spring and summer) corresponded to secondary factor. The reduction of the average sward height to 15cm in the winter resulted, when compared with pasture maintained at 25cm, in overall higher growth rates (95kg/ha.day DM) and leaf blade (66.1kg/ha.day DM), as well as higher rates of total accumulation (81.5kg/ha.day DM) and leaf blade (52.6kg/ha.day DM). The accumulated forage production (from winter to summer) was higher in the pasture lowered to 15cm in winter (25.6t/ha DM) compared with that managed with an average height of 25cm (22.2t/ha DM). Regarding the seasons of the year, in the winter, there were lower rates of overall growth (6.4kg/ha.day DM), leaf blade (5.6kg/ha.day DM) and pseudostem (0.8kg/ha.day DM), and also lower total (-6.6kg/ha.day DM) and leaf blade (-7.5kg/ha.day DM) accumulation rates. In the spring there was a higher rate of leaf senescence (22.4kg/ha.day DM). The accumulation of forage is incremented when the pasture of B. decumbens is lowered to 15cm during the winter, and in the spring and summer, its average height is increased to 25cm. © 2013 Sociedade Brasileira de Zootecnia.