Management of native warm-season grasses for beef cattle and biomass production in the Mid-South USA1

Abstract

Native grasses, such as switchgrass (SG; L.), big bluestem (BB; Vitman), indiangrass (IG; Nash), and eastern gamagrass (EG; [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 () 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 ( < 0.05) for BBIG (1.02 kg/d) than SG (0.85 kg/d), and both were greater ( < 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 ( < 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.

Winter grazing stockpiled native warm‐season grasses in the Southeastern United States

“…Performance of BBIG during the autumn 2016 drought was poor, resulting in no overall HM differences between BBIG and TF. This contrasts with general observations of increased HM in NWSG and expectations of increased drought performance in C 4 species (Backus et al., ).…”

“…Native warm‐season grasses (NWSG) are an alternative forage system (Backus et al., ). These grasses are foundation species to many endangered local ecosystems (Noss, ).…”

“…These grasses are foundation species to many endangered local ecosystems (Noss, ). During summer, NWSG support economically competitive rates of animal gain (Backus et al., ; Bonin & Tracy, ; Lowe et al., ). The utilization of NWSG pastures to complement TF pastures could improve forage availability during summer and drought conditions.…”

Overseeding cool‐season annual grasses into dormant lowland switchgrass stands

“…Increased use of switchgrass (SG), a warm-season perennial grass, as a biomass crop has the potential to displace forage production (Backus et al, 2017;Lowe et al, 2016;McIntosh et al, 2016). Furthermore, SG, regardless of the production model (forage, biomass, or both), does not produce biomass or forage during its dormant period (November-March), leaving an underutilized land resource.…”

“…Additional research is needed to help determine the feasibility of a system where winter annuals can be overseeded into dormant switchgrass. Such an approach could increase overall yield per hectare (Foulia et al, 2012) and offset lost forage production associated with biomass production (Backus et al, 2017). Therefore, an experiment was implemented to determine the productivity and economic feasibility of establishing three CAGs (rye, ryegrass, and…”