CHEMICAL COMPOSITION OF THE KING GRASS (Pennisetum purpureum Schumach) AT DIFFERENT CUTTING INTERVAL

Abstract

The objective of this experiment was to evaluate the effect of cutting interval on chemical composition and in vitro dry matter digestibility (IVDMD) of king grass (Pennisetum purpureum Schumach). Samples of four cutting intervals: 90, 120, 150 and 180 days after regrowth, were analyzed. The IVDMD, and proximate and Van Soest analyses were determined on leaf, shoot and the complete plant. Lignin increased while crude protein, ether extract and IVDMD decreased as cutting interval increased (P<0.05). The best cutting interval was between 90 and 120 days after which IVDMD begins to decrease probably because, from 120 days onwards, crude protein and ether extract decreased and lignin increased. It is concluded that quality of king grass decreases as the cutting interval increases, independently of the morphological component, and in turn, increases cell wall components, such as lignin.