In Situ Dry Matter, Nitrogen, and Fiber Degradation of Alfalfa, Red Clover, and Eastern Gamagrass at Four Maturities

Abstract

This study compared in situ degradation characteristics of dry matter, N, and neutral detergent fiber (NDF) for alfalfa and red clover with those for eastern gamagrass, a perennial, warm season grass that is native to the Flint Hills of Kansas. Gamagrass had a high proportion of leaf tissue (>69%) at boot and anthesis stages, at physiological maturity, and after 56 d of regrowth following clipping at boot stage. Gamagrass also had high N concentrations at boot and anthesis stages (2.82 and 2.16%, respectively). Whole-plant gamagrass tissue contained a large proportion of N that was insoluble in neutral detergent (>51%); however, this was a characteristic only of leaf tissue and was observed on a whole-plant basis because of the large proportion of leaf tissue at all plant maturities. Degradation characteristics of dry matter and NDF generally indicated that stem and cell-wall components from gamagrass at boot and anthesis stages had large maximum extents of degradation. Nitrogen degradation rates (0.047 to 0.059/h) were slower for whole-plant gamagrass than for alfalfa (0.213/h). The most distinguishing characteristic of these findings was not that N from gamagrass degraded more slowly in the rumen than did N from alfalfa or red clover, but that this trait was coupled with N concentrations at harvestable growth stages (boot or anthesis stages) that were similar to legumes.