Nutritional evaluation of Braquiaro grass in association with Aroeira trees in a silvopastoral system

This study aimed at evaluating the influence of a silvopastoral system (SPS) composed of Aroeira trees (Myracrodruon urundeuva) on the nutritional value of Brachiaria brizantha cv. Marandu forage grass over the rainy season. The experiment was conducted in the SPS located in the Cerrado biome in Lagoa Santa County, Minas Gerais state, Brazil, in the agricultural year of 2004-2005. It was evaluated the influence of Aroeira, whose density in the area was 140 trees/ha, on the following parameters of the B. brizantha cv. Marandu forage grass: forage mass harvest above stubble height, morphogenic attributes, bromatological composition and nutritional value. The effects of Aroeira trees on the micro-climatic conditions were also evaluated. The experiment adopted a randomized block design with five blocks (cutting seasons), two treatments (a shaded pasture-B. brizantha cv. Marandu shaded by M. urundeuva-and a pasture in full sun-B. brizantha cv. Marandu in full sun), and three replicates. The tree component, composed of the tree species M. urundeuva in the experimental density adopted, increased dry matter and crude protein of the forage mass harvest above stubble height, without affecting the concentration of neutral detergent fibre or acid detergent fibre, thus causing dry matter and organic matter in vitro degradability as well as effective degradability of the forage grass to remain the same as those obtained in full sun. Therefore, the results of this study show the possibility of using trees and grass to increase both animal production and environmental services.