Dinâmica Produtiva e Valor Nutritivo de Pennisetum purpureum (Schumach) cv. BRS Kurumi sob diferentes alturas pré e pós desfolha

Abstract

The objective of this work was to evaluate the productivity, distribution of production and nutritional value of forage and tillering of elephant grass cv. BRS Kurumi under different heights of canopy pre and post defoliation (residue). The treatments were distributed in a randomized complete block design with two pre defoliation canopy heights (60 and 80 cm) and three post-defoliation (10.25 and 40 cm) heights, with four replications, combined in arrangement factorial 2 x 3 being respectively 60 x 10 cm; 60 x 25 cm; 60 x 40 cm; 80 x 10 cm; 80 x 25 cm; 80 x 40 cm. The productive, bromatological, carbohydrate fractionation and in situ degradability characteristics were evaluated. The data were submitted to analysis of variance, adopting the level of significance of 5 %. The averages were adjusted by LSMEANS (Least Squares Means) and analyzed by the adjusted Tukey's test. For green forage mass, treatments 60x10 and 80x10 presented higher yield, producing 15247 and 36350 t / ha respectively. The accumulation rate was higher in the heights of 80 cm. For basal tiller 80x40 presented 52 tiller m², and tiller 80x25 had 200 tiller m2 . No effects of treatments for neutral detergent fiber (NDF), acid detergent fiber, and ethereal extract were observed. The highest dry matter (DM) yield per cut was found in the residues of 40 cm (11.4 %). The crude protein content presented higher results for canopy heights of 60 cm (19.3 %) and residues of 40 cm (19.4 %). Total carbohydrates presented higher values for canopy heights of 80 cm (65.4 %), with fraction A + B1 (14 %), fraction B2 (73.5 %) was higher in the 60 cm canopy, and the fraction C (16.4 %) in the 80 cm canopy. The digestibility coefficients of 24 (76.8 %) and 48h (85.3 %) of DM and 24 (60.3 %) and 48h (74.8 %) of NDF were higher for canopy heights 60 cm. In the elephant grass cv. BRS Kurumi, when short grazing intervals associated with higher forage quality were observed, the 60x25, 60x40 and 80x40 maneuvers are the most indicated. When the objective is the maximum production of dry matter by defoliation and total forage production, the 80x10 and 80x25 managements are the most advised. From the point of view of tiller production, 80 cm canopy management is preferred, with 80x25 for aerial tillers and 80x40 for basal tillers.