Uso de animais na avaliaçao de forrageiras

The evaluation of forages with animals under grazing systems is an area of extreme importance for beef cattle production in the world, and especially for tropical and subtropical countries like Brazil. This is so, because Brazil has as a characteristic and also, as economic advantage the fact that its beef production systems are based mainly on pastures. However, in order to make the results obtained from this type of evaluation more attractive as far as practical point of view is concerned, and more interesting under economic aspects as a result of increments in productivity; and at the same time, being able to guarantee the biological efficiency of the production systems, it is necessary to have these evaluation carried out considering the existence of two systems, forage and animal, which are very well defined. Not only these two systems are important, but so are the relationships between them. In addition to that it is necessary a good understanding of the complex soil-plant-animal. Under this context, this paper looks for discussing not only the isolated systems, but also it tries to evidence areas of relationships and the steps necessaries for reaching the desired results, which are not only an evaluation applicable to the productive sector, but also that it results in productions systems which are bioeconomically viable and sustainables. eng