Estratégias de manejo do capim mavuno no ecótono Cerrado-Amazônia

Abstract

The objective of this study was to evaluate forage accumulation and nutritive value of ‘Mavuno’ brachiariagrass under management strategies during the growing season (Exp. 1) and dry season (Exp. 2) in the Cerrado-Amazonian ecotone. The research projects were conducted at the Escola de Medicina Veterinária e Zootecnia of Universidade Federal do Tocantins in 2017 and 2018. In Exp. 1, treatments were the factorial arrangement of two brachiaria grass cultivars, ‘Marandu’ (Urochloa brizantha) and ‘Mavuno’ (Urochloa brizantha x Urochloa ruziziensis) harvested at two stubble heights, 5 or 15 cm, distributed in a randomized complete block design with four replicates. Response variables were forage height, forage accumulation, proportion of leaf, stem and dead material, crude protein (CP), in vitro digestibility of organic matter (IVOMD) concentration and leaf:green material ratio. ‘Mavuno’ and ‘Marandu’ did not differ in forage accumulation, while the 5 cm stubble height had greater forage accumulation than 15 cm (4094 vs. 3524 kg/ha/cycle). Mavuno had lesser accumulation of dead material (128 kg/ha/cycle) compared to Marandu (206 kg/ha/cycle). In Exp. 2, treatments were the factorial arrangement of two N fertilization levels, 50 or 100 kg/ha, and 4 stockpiling periods, 60, 90, 120 and 150 d. Response variables were pasture height, extended pasture height, falling index, forage accumulation, accumulation and proportion of leaf, stem and dead material, leaf:green material ratio, crude protein and IVOMD. There was no influence of nitrogen fertilization on any response variable. Forage and stem accumulation had a quadratic effect, with maximum accumulation of 5718 kg/ha at 133 d and 2287 kg/ha at 125 d of stockpiling period, respectively. Mavuno grass has potential for the Cerrado-Amazonian ecotone, with herbage accumulation and nutritive value similar to Marandu in the rainy season. Mavuno grass may be an alternative to be stockpiled for winter grazing with 120 d stockpiling period and nitrogen fertilization of 50 kg/ha.