Nutritive Value of Clipped ‘Mott’ Elephantgrass Herbage

Abstract

AbstractMany tropical grasses are low in nutritive value, but ‘Mott’ dwarf elephantgrass (Pennisetum purpureum Schumacher) has supported gains of yearling cattle (Bos taurus) approaching 1 kg d−1. To aid in identifying optimum harvest management practices for Mott, this study quantified crude protein (CP) and in vitro digestible organic matter (IVDOM) concentrations of leaf blade, leaf sheath, stem, and total herbage harvested following imposition of a wide range of clipping treatments. Treatments in 1989 and 1990 included all 16 combinations of four defoliation frequencies (3, 6, 9, and 12 wk) and four stubble heights (10, 22, 34, and 46 cm) in a randomized block design with three replicates. The soil was a hyperthermic, uncoated Aquic Quartzipsamment (Adamsville series). Data were analyzed by fitting multiple regression equations starting with a second‐order polynomial model. The range in IVDOM of total herbage harvested was from 653 to 791 g kg−1 (1989) and 680 to 739 g kg−1 (1990). Frequent defoliation to short stubble resulted in greatest IVDOM; herbage harvested infrequently to short stubble was least digestible. Total herbage CP ranged from 87 to 140 g kg−1 in 1989 and 89 to 133 g kg−1 in 1990, and was greatest with frequent harvest to a tall stubble. Mott elephantgrass CP and IVDOM were high across a wide range of defoliation frequencies and stubble heights. Because of Mott's high nutritive value even when defoliated infrequently (e.g., 9 wk), achieving yield and persistence goals can be the primary basis for selecting defoliation management practices.