ABSTRACT
Summary Agronomic evaluation of the dynamics of tropical legume-based pastures is relevant in assessing the response of their components within systems of grazing management. The response of tropical legume-grass mixtures to periods of rest and grazing pressure and the combinations that result in meaningful legume content in the mixture need to be known. A central composite design was used to study the performance of a Desmodium intortum (Mill.) Urb. and Paspalum guenoarum Arech. pasture mixture to 14, 28, 42, 56, and 70 days of rest combined with 2.0%, 3.5%, 5.0%, 6.5%, and 8.0% BW (i.e., kg dry matter (DM) on offer/day/100 kg body weight) as grazing pressure, in a rotational grazing system. Forage DM yield and botanical composition were assessed by a double-sampling procedure. Pasture parameters were analyzed by a second-degree polynomial, and canonical analysis facilitated the interpretation of pasture performance. Daily pasture DM yield tended to increase under lenient grazing pressure, while higher percentages of contribution and survival of P. guenoarum and D. intortum were achieved with longer rest periods. The invasion of other grasses increased with short periods of rest and higher grazing pressure. Weeds were present at very low levels. The stocking rate increased with increasing grazing pressure, but forage consumption/animal tended to increase under lenient grazing pressure combined with long rest periods. P. guenoarum and D. intortum assure good-quality feed at long periods of rest. Long rest periods are required to maintain D. intortum and P. guenoarum as active components of the pasture sward and can effectively contribute to forage feeding systems in the tropics.
