Review: Quality Characteristics of Eastern Gamagrass Forages11Contribution Number 99010 of the Arkansas Agricultural Experiment Station

Eastern gamagrass [Tripsacum dactyloides L.] is a native, warm-season, perennial, bunch-type grass adapted generally to moist sites throughout much of the eastern United States. Nitrogen concentrations of eastern gamagrass will normally exceed 20 g/kg at growth stages (boot and anthesis) that produce reasonable yields. With moderate N fertilization, concentrations of N approaching 32 g/kg are realistic in whole-plant tissue harvested at boot stage in the upper Midwest. Recent studies suggest that high proportions (>50%) of this N are insoluble in neutral detergent (NDIN), thereby implying association with the cell wall. In situ studies in Kansas have shown that the potential extent of ruminal N degradation for gamagrass harvested at boot stage is comparable with that of high quality legumes, but degradation occurs at slower rates; generally, similar trends have been observed for in situ disappearance of DM and fibrous components. Increasing plant maturity appears to limit extent primarily, but not the rate, of degradation for these plant components. Concentrations of NDF are generally high (>600 g/kg), even at immature growth stages; this observation is consistent with findings for other warm-season grasses. In studies conducted throughout the mid South, researchers report that ADG ranged between 0.5 and 1.0 kg/d for steers continuously grazing eastern gamagrass pastures. Daily gains are likely to be reduced as days on pasture increase. Mounting evidence suggests that gamagrass grown in the Midwest demonstrates better quality characteristics than that grown in the Southeast.