Productivity and nutritional value of BRS capiaçu grass (Pennisetum purpureum) managed at four regrowth ages in a semiarid region.

Abstract

The objective of this study was to evaluate the productivity, productive efficiency, and nutritional value of the elephant grass cultivar BRS capiaçu (Pennisetum purpureum Schum.), managed at four regrowth ages during winter in the semiarid region of northern Minas Gerais, Brazil. A completely randomized design with the elephant grass cultivar BRS capiaçu was submitted to four cut intervals (30, 60, 90, and 120days) in the winter with ten replications, for a total of 40 plots, each with a useful area of 6 × 5m. There was a linear increase of 76.25% (P < 0.01) in the height of BRS capiaçu grass when cut from 30 to 120days. Green matter production (P < 0.01) and dry matter production (P < 0.01) increased daily by 1081kg/ha and 237kg/ha, respectively. The annual dry matter production was 72t/ha. Efficiency in water use changed (P < 0.01) from 7.91kg of dry matter (DM)/mm at 30days to 57.59kg of DM/mm at 120days of regrowth. There was a reduction in the ash content (P < 0.01), crude protein (P < 0.01), and the total digestible nutrient content (P < 0.01) with the increase in the age of the cut. The readily soluble fraction of DM (fraction A, P < 0.01), degradation rate "c" of insoluble fraction "B" (P = 0.01), potential degradability (PD; P < 0.01), and degradability (ED; P < 0.01) decreased linearly as the regrowth age increased. Harvesting is recommended at 90days of regrowth during the winter season in this semiarid region.