SILVOPASTORAL SYSTEMS AS A SUSTAINABLE ALTERNATIVE TO ANIMAL PRODUCTION IN THE TROPICS

The increasing number of cattle in Brazil indicates their economically positive benefit however, they are also one of the major causes of environmental degradation. In Brazil, deforested areas are mainly used for pastures and while these are very productive initially, have generally degraded within a five year period. These poor quality pastures generate low, uneconomic levels of milk and beef production, with the resulting poverty causing rural populations to increasingly migrate to urban areas. Therefore, to reduce the negative impacts of livestock on the environment and communities, sustainable alternative animal production techniques have need to be developed and adopted. The silvopastoral systems (SPS) which encompass agriculture (legumes, grasses, trees etc.) and livestock (principally cattle and sheep) have demonstrated that it is possible to combine animal production, environmental conservation and social benefits. The trees in the SPS enhance nutrient uptake from the soil, which is then passed to the grass through the degradation of organic matter (e.g. leaf loss) so improving both soil fertility and forage quality. The trees also enhance animal welfare due to the lower shade temperatures and increased humidity, can be a source of wood (timber and fuel), bio-diesel, as well as improving environmental aspect e.g. aesthetics, reducing soil erosion and water loss and increasing bio-diversity. The results of the research are contradictory and specific for each SPS evaluated as they vary according to the grass and tree species used, the weather and soil conditions and the management applied. Several experiments have shown lower forage production under the trees, even though protein content was improved and therefore of a better nutritional quality for animal production. However, only in few studies under tropical conditions were environmental and social aspects evaluated directly. In order to apply the concept of sustainable agriculture and livestock production developed by the Food Agriculture Organization (FAO), it is necessary to expand the narrow view taken so far by research. To achieve this production has to evaluated, not through one particular aspect, but from a more holistic point of view in which the economic, social and environmental results are integrated.