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Agroforestry systems (AFS) in general and silvipastoral systems (SPS) in particular, have been studied intensively in Brazil since the 1980's. The majority of the research work has been conducted in the wet tropical Amazon region, in the semi-arid conditions of the Northeast, and under subtropical soil and climatic conditions in the Southeast or in the South. Research emphasis has been placed on interactions between the main components of AFS: tree, pasture, soil and microclimatic elements. Evaluation of animal performance in SPS generally has not been the main objective of experiments. A recent survey of research on SPS using Eucalyptus spp. in Brazil, showed that only 6.5% of the references in such articles pertained to the productive performance of sheep and beef cattle under grazing (Couto et al., 1998). In the Tropics, the native rain forest is the most important arboreal substrate, because it has to be preserved for environmental and biodiversity maintenance. Accordingly, research has focused on identification of either native or exotic timber tree/palm tree species to be used in SPS. At the present time, SPS using species of Pinus, rubber tree, mango tree, brazilian chestnut tree and coconut tree are common in this region. Brachiaria brizantha cv. Marandu, B. humidicola, Paspalum atratum BRA-009610, Desmodium ovalifolium CIAT-350, Pueraria phaseoloides BRA-0612 and Centrosema macrocarpum CIAT-5065 are some of the shade tolerant forage species showing promise for SPS in the Amazon region. In the Caatinga ecosystem, in the Northeast, research has shown that browsing of native shrubs associated with the utilization of Leucaena leucocephala protein bank and/or buffelgrass pasture allows substantial increases of liveweight gain or milk production by sheep, goats and dairy cows. In the Southeast region, in Minas Gerais and Sao Paulo states, SPS consist mainly in the association of Eucalyptus spp and Panicum maximum. Studies involving two-year-old eucalypt plantations showed that sheep or beef calves grazing P maximum cv. Coloniao allowed from 52 to 93% reduction of forest establishment and maintenance costs, as a result of selling animal products and reduction of grass competition by grazing. In the South, the most important exotic arboreal materials are Eucalyptus, Pinus and Acacia species, while Mimosa scabrella and Araucaria angustifolia are potential useful native trees. Species of Trifolium and annual ryegrass (Lolium multiflorum) mixtures have been used as cool-season pastures while P. maximum cultivars and B. brizantha cv. Marandu are used as warm-season pasture grasses. Beef calf liveweight gains on SPS consistently outyielded those obtained by grazing the native pasture in full sunlight, at two locations in Rio Grande do Sul state.

Although there is a reasonable amount of information on the establishment and management of SPS within each ecoclimatic brazilian region, the level of adoption of this new technology at the farm level is still considered very low. The benefits and possible eventual adverse consequences of the tree x pasture association on animal production, along with a discussion of the future prospects of research and potential adoption of SPS in Brazil are addressed in this paper.