Evaluation of two Panicum maximum cultivars under two nitrogen rates, in rotational stocking by sheep

Abstract

The present study was carried out at Instituto de Zootecnia, Nova Odessa - SP. The objective was to evaluate: forage mass and their components, forage accumulation, daily forage accumulation rate, and sward height from two Panicum maximum Jacq. cultivars (Aruana and Tanzania), under two nitrogen rates (150 and 300kg ha-1 de N), and grazed by sheep in rotational stocking with three to seven grazing days and variable resting periods. The variables were evaluated in six, seven and eight grazing cycles in the first, second and third experimental years, respectively. The experimental design was in complete randomized block (four) with two replicates within each block, with grasses as plots (paddocks) and the nitrogen rates as sub-plots, with repeated measures in time. Tanzania grass presented more annual forage accumulation than Aruana grass only in the third experimental year and more daily forage accumulation rate in the second and third years. It showed greater height and forage mass left after grazing than Aruana grass because it presents thicker and stiffer stems that makes difficult the sward lowering by animals. The rate of 300kg of N/ha/year presented greater values than the one of 150kg in the total forage accumulation rate. But when it is considered the ratio: quilogram of forage mass produced per quilogram of nitrogen applied it was less efficient than the one of 150kg.