Produtividade e Valor nutritivo dos capins Piatã, Zuri e Tamani em sistemas ILPF na Região Central de Minas Gerais

Abstract

The objective was to evaluate the productivity and the agronomic and bromatological parameters of Urochloa brizantha cv. Piatã, Megathyrsus maximus cv. Zuri and Megathyrsus maximus cv. Tamani, in silvopastoral systems (SSP) with different tree densities and in full sun pasture. The test was carried out in the experimental field of Embrapa Milho e Sorgo, in the municipality of Sete Lagoas, Minas Gerais. The experimental design adopted was completely randomized, with plots subdivided in space, with six replications. The plots corresponded to four spatial arrangements: three arrangements of SSP with Eucalyptus grandis GG100 (15×2, 15×4 and 15×8 m) and a monoculture of grasses. The subplots were composed of three grass cultivars: U. brizantha cv. Piatã, M. maximus cv. Zuri and M. maximus cv Tamani. The subplots consisted of four cuts 20 cm above the soil surface, with six replications in each. The incident solar radiation on the canopy of each treatment was evaluated and the forage biomass productivity and the proportion of leaf and stem components in the forage biomass were determined. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (LIG), mineral matter (MM) was evaluated in the forage biomass and leaf components and in vitro dry matter digestibility (IVDM). The shading caused by the eucalyptus rows in the SSPs positively impacted forage quality, especially the CP content, in relation to forage produced in full sun. Evaluating the amounts of trees per hectare of 166 trees/ha and 333 trees/ha in the SSPs, the studied pastures suffered significant reductions in incident solar radiation and, consequently, significant reductions in the production of whole plant biomass, leaves and stems in forage when compared to pasture in full sun, but surprisingly, the tree density of 84 trees/ha, was statistically equally productive to PS. The cv. Zuri showed the best forage mass productivity results at PS and at different tree densities. The average values of CP found in the evaluations of cv. Tamani (14- 18% p<0.01), proves to be an important factor for the use of the cultivar, with the potential for high productivity in dairy and beef cattle per animal. The treatment with 84 trees/ha results in the same productivity indexes as the PS, with an increase in the chemical quality of the pastures. Thus, spacing becomes recommended for producers who wish to implement an ILPF, combining its benefits, without losing productivity.