Productive and nutritional characteristics of Piatã-grass in integrated systems

SUMMARY This study aimed to evaluate the pasture productive and nutritional characteristics of Brachiaria brizantha cv. BRS Piatã in integrated systems with different densities of trees. Considering as plot the systems: integrated crop-livestock-forest with rows of trees (eucalyptus) spaced at 14 m and 357 trees ha-1 (ICLF-14m), ICLF with rows of trees spaced at 22 m and 227 trees ha-1 (ICLF-22m) and the integrated crop-livestock (ICL) with five remaining native trees ha-1; period of the year as subplots, and sampling points as subsubplots (A, B C, D, and E) arranged perpendicular to trees alleys. It was evaluated the production of forage and leaf blade dry mass, leaf:stem ratio, soil coverage, radiation photosynthetically active interception, canopy height, crude protein (CP), neutral detergent fiber (NDF), in vitro digestibility of organic matter (IVDOM) of the leaf blade, and stem associated with the leaf sheath. There was a significant difference (P<0.05) for all variables due to the month within the integrated systems. Mainly in January and March, showing the forage and leaf blade dry mass reduction due to a higher trees density. System with higher trees density showed the lowest soil coverage and canopy height sampling points A and E in ICLF-22m showed lower forage and leaf blade dry mass production and soil coverage. The system with higher trees density showed lower value of NDF of the leaf blade, and higher CP contents. The IVDOM of the leaf blade was higher in ICLF systems. For the evaluated parameters the best results were for the ICLF-22m.## 摘要 本研究旨在评估不同树木密度复合系统中Brachiaria brizantha品种BRS Piatã（Brachiaria brizantha cv. BRS Piatã）的牧草生产与营养特性。试验以复合系统为小区：①桉树带行距14m、每公顷357株的农-林-牧复合系统（ICLF-14m）；②桉树带行距22m、每公顷227株的农-林-牧复合系统（ICLF-22m）；③每公顷保留5株原生树木的农-牧复合系统（ICL）；以年度生长时期为副小区，以垂直于林带布置的采样点（A、B、C、D、E）为副副小区。本研究测定的指标包括牧草与叶片干物质产量、叶茎比、土壤覆盖度、光合有效辐射截获量、冠层高度、叶片粗蛋白（crude protein, CP）、中性洗涤纤维（neutral detergent fiber, NDF）、叶片体外有机物消化率（in vitro digestibility of organic matter, IVDOM），以及附随叶鞘的茎秆相关指标。结果显示，各复合系统内所有测定指标均存在显著月份差异（P<0.05），其中1月与3月的差异最为显著，较高树木密度的系统牧草与叶片干物质产量出现下降。树木密度更高的系统土壤覆盖度与冠层高度更低；ICLF-22m系统的采样点A与E的牧草与叶片干物质产量、土壤覆盖度均较低。树木密度更高的系统叶片中性洗涤纤维（NDF）含量更低，而粗蛋白（CP）含量更高。农-林-牧复合系统的叶片体外有机物消化率（IVDOM）更高。综合所有测定参数，ICLF-22m系统表现最优。