\u3cem\u3eIn Situ\u3c/em\u3e Digestibility of \u3cem\u3eGliricidia sepium\u3c/em\u3e Combined with \u3cem\u3eBrachiaria decumbens\u3c/em\u3e in a Silvopastoral System

Silvopastoral system (SPS) are characterized by a combination of trees, pasture and herbivores animals, in the same physical area, in order to obtain diversified products. A promising legume tree that has been studied and used in SPS in tropical areas is gliricidia [Gliricidia sepium (Jacq.) Steud]. Advantages of gliricidia use in SPS include N inputs via biological fixation, improvement of soil properties, nutrient cycling and also a source of feed to grazing animals (Cubillos-Hinojosa et al., 2011). Gliricidia has high crude protein concentration in its leaves, which complements the usual N-poor diet of ruminants grazing warm-season grasses. The introduction of gliricidia in SPS faces a problem due to the low initial acceptability by cattle, being necessary an adaptation period in order to cattle reach satisfactory intake levels (Carvalho Filho et al., 1997). In general, the quality of the forages can be predicted by accessing their nutritive value, represented by the chemical composition and digestibility of the forage constituents (Van Soest, 1994). The digestibility of dry matter in forages consumed in a SPS can be influenced by the forage species used, by grass/legume combinations, and by the proportion that each forage species takes in the diet of the ruminants. This study evaluated in situ digestibility of gliricidia in increasing levels of inclusion in the diet composed by sabi grass (Brachiaria decumbens, Stapf) in a silvopastoral system

Relationship between Field Measurements in Three \u3cem\u3eBrachiaria\u3c/em\u3e Species with Leaf Area Index and Light Interception by Indirect Methods

Brachiaria species play a strategic role in ruminant production systems in Brazil, covering an estimated pasture area of approximately 90 million hectares (Karia et al., 2006), however, these pastures are subject to different degrees of degradation due to inadequate management. In pasture management, field measurements such as canopy height, for example, are used by managers as a tool to establish parameters for the optimal point to cut the forage and for the post-grazing residue, in order to maximize production by harvesting at maximum of herbage mass accumulation, and to avoid problems associated to overgrazing, by setting ideal post-grazing height for forage regrowth. The use of the variables light interception (LI) and leaf area index (LAI) has been recommended as a tool for pasture management, based on the theory that, when the canopy reaches a light interception of 95%, the forage is near its maximum growth rate, which is called critical LAI (Brougham, 1956). The residual LAI refers to the leaf area of the post-grazed stubble. Residual LAI is used to establish the minimum leaf area necessary to ensure an efficient pasture regrowth (Lemos et al., 2014). Light interception and the LAI are difficult to measure at the farm level, due to the high cost of the equipment and technical feasibility of the process. The objective of this study was to evaluate the relationship between LI and LAI measured by two different equipment, with canopy height and soil cover in three species of Brachiaria