Management of native warm-season grasses for beef cattle and biomass production in the Mid-South USA

Native grasses, such as switchgrass (SG; Panicum virgatum L.), big bluestem (BB; Andropogon gerardii Vitman), indiangrass (IG; Sorghastrum nutans Nash), and eastern gamagrass (EG; Tripsacum dactyloides [ L.] L.) may be capable of providing desirable summer forage for cattle as well as a source of biomass for renewable energy. To evaluate that potential, experiments were conducted at 2 locations in Tennessee comparing weaned beef (Bos taurus) steers (268 +/- 25 kg initial BW) during early-season grazing (Early; 30 d, typically corresponding to May, followed by postdormancy biomass harvest) and full-season grazing (Full, mean duration = 98 d). For Exp. 1, which compared SG, a blend of BB and IG (BBIG), and EG, ADG was greater (P < 0.05) for BBIG (1.02 kg/d) than SG (0.85 kg/d), and both were greater (P < 0.05) than EG (0.66 kg/d). Grazing days for SG and EG were similar (389 and 423 animal unit days [AUD]/ha, respectively) and exceeded (P < 0.05) that of BBIG (233 AUD/ha) during Full. In Exp. 2 (SG and BBIG only), rates of gain were comparable to that of Exp. 1, but AUD were 425 (SG) and 299 (BBIG) AUD/ha. Such rates of gain and grazing days indicate that these grasses can provide desirable summer forage for growing cattle. Early produced 211 to 324 kg BW gain/ha, depending on experiment and forage, followed by dormant-season harvests of 7.5 to 10.5 Mg/ha of biomass, indicating a potential for beef cattle forage and biomass production on the same land resource. Native grasses provided productive summer pasture and good rates of gain on growing cattle and could contribute to forage programs, especially where cool-season grasses currently predominate.