Nutritional value of Mombasa grass submitted to different grazing heights and nitrogen fertilization / Valor nutritivo do capim-Mombaça submetido a diferentes alturas de pastejo e adubação nitrogenada

Abstract

We evaluate the effect of sward height (0.20 and 0.40 m) and N-fertilizer doses (0, 100, 300, and 500 kg ha -1 ) on the nutritive value of Mombaça guinea grass ( Panicum (syn: Megathyrsus ) maximum (Jacq.)) in the dry and rainy season. The experiment was a complete random block design with a 4 x 2 factorial arrangement, in a split-plot experiment with four repetitions. Dry matter, crude protein, neutral detergent fiber, acid detergent fiber, lignin, and in vitro dry matter digestibility were stated for the whole plant and fractions. Residual heights did not interfere (P>0.05) on production or nutritive value. N doses influenced (P<0.05) of the whole plant, leaf blade and stem nutritive value in both seasons. Higher crude protein contents were obtained with higher N doses and ranged around 10%. The mean whole plant NDF levels were 74.5% (rainy season) and 75.5% (dry season). In vitro dry matter digestibility level increased as N doses increased. The nutritive value of the mombaça grass submitted to cutting heights and nitrogen doses was positively altered. It is recommended the management of the mombaça grass with a forage residue of 0.40 m and application of up to 300 kg.ha -1 of nitrogen during the rainy season of the year.