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Grazing management guide in signal Grass (Brachiaria decumbens Stapf. cv. Basilisk) pastures

Abstract

Most Brazilian grazing trials with tropical grasses ignore plant and canopy attributes, determinants of herbage and animal performance and that would have to guide defoliation strategies. The species Brachiaria decumbens, although to keeping as forage grass more cultivated in Central Brazil for long years, does not have objective and precise targets about your defoliation management. In this way, the objective of this study is to propose, based in sward structure and plant morphogenesis, options to grazing management in signal grass (Brachiaria decumbens Stapf. cv. Basilisk) pastures. The study will be carrying out in the Unidade de Pesquisa e Desenvolvimento at Brotas-SP of the Agência Paulista de Tecnologia do Agronegócio (APTA), and will be divided in three phases, called experiments 1, 2 and 3. The experiments will be conducted in signal grass pasture under soil type classified as typic quartzipsamment. Each experiment will last from beginning of raining season to beginning of dry season of the following year, approximately from September to June. In the experiment 1, the treatments will be four stubble heights (5, 10, 15 and 20 cm) in a completely randomised experimental design with four replications. During free regrowth of grass will be evaluated in individual tillers, leaf appearance rate (LAR), leaf elongation rate (LER), leaf senescent rate (LSR) and stem elongation rate (SER). The sward structure components as sward eight, light interception (LI) and leaf area index (LAI) will be evaluated weekly. In the experiment 2, two grazing frequencies (F) and two grazing intensities (I) treatments will be defined after experiment 1 results obtainment. The defoliation will be realized by cross steers and the experimental design will be completely randomised, in a factorial arrangement with four replications. Such as experiment 1 morphogenesis and sward structure will be evaluated. The experiment 3 will have three sward height treatments (10, 17, 5 and 25 cm), kept constants under continuous stocking in defoliation realized by cross steers. The experimental design will be completely randomised with three replications. The morphogenesis and sward structure will be evaluated such as experiments 1 and 2, out the former measured in 20-days periods and the latter measured monthly. (AU)