IN-SITU DRY-MATTER, NITROGEN, AND FIBER DEGRADATION OF ALFALFA, RED-CLOVER, AND EASTERN GAMAGRASS AT 4 MATURITIES

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 na tive to the Flint Hills of Kansas. Gamagrass had a high proportion of leaf tissue (> 69%) at boot and anthesis stages, at physiological matu rity, and after 56 d of regrowth following clipping at boot stage. Gam agrass also had high N concentrations at boot and anthesis stages (2.8 2 and 2.16%, respectively). Whole-plant gamagrass tissue contained a l arge proportion of N that was insoluble in neutral detergent (> 51%); however, this was a characteristic only of leaf tissue and was observe d on a whole-plant basis because of the large proportion of leaf tissu e at all plant maturities. Degradation characteristics of dry matter a nd NDF generally indicated that stem and cell-wall components from gam agrass at boot and anthesis stages had large maximum extents of degrad ation. Nitrogen degradation rates (0.047 to 0.059/h) were slower for w hole-plant gamagrass than for alfalfa (0.213/h). The most distinguishi ng characteristic of these findings was not that N from gamagrass degr aded more slowly in the rumen than did N from alfalfa or red clover, b ut that this trait was coupled with N concentrations at harvestable gr owth stages (boot or anthesis stages) that were similar to legumes.