Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1993
Publication Date: N/A
Interpretive Summary: Switchgrass has recently been found to be a valuable forage when either grazed or conserved for hay. Because of the high frequency of thunderstorms in the humid Southeastern USA, switchgrass is difficult to dry without exposure to rain. Switchgrass that has been mowed then rained on begins to rot. The conservation of switchgrass as silage would avoid this problem. Switchgrass that was direct cut (about 25% dry matter) or wilted (about 35% dry matter) resulted in very acceptable silage. Immature switchgrass was preserved better than mature (headed) switchgrass. Because of its high cell wall and low cell soluble concentrations, switchgrass forage must be chopped and well packed to exclude oxygen. Steers consumed either direct cut or wilted silage as well as barn-dried hay. Switchgrass can be grazed or conserved as either hay or silage.
Technical Abstract: Switchgrass (Panicum virgatum L.) harvested in the vegetative, late boot, and fully headed stages was readily ensiled when either directly cut and stored at a dry matter (DM) concentration of about 250 g/ kg or wilted and stored at a DM concentration of about 350 g/kg. Silage pH ranged from 4.6 to 5.1 for all treatments with acetic and lactic acid predominating. Acetic acid ranged from 19 to 21 g/kg in the direct cut silage and from 9 to 10 g/kg in the wilted silage. Lactic acid ranged from 13 to 28 g/kg in the direct cut silage and from 17 to 28 in the wilted silage. Forage at ensiling was high in cell walls (694 to 743 g/kg) and low in crude protein (53 to 63 g/kg). Silage was stable when either direct cut or wilted and well preserved when air was excluded. Preservation as artificially-dried hay or ensilage (direct cut or wilted) did not alter DM intake (kg/100kg body weight) which averaged 1.48 for the late boot and 1.41 for the fully headed stages. Apparent digestion coefficients for DM and cell wall constituents of fully headed switchgrass showed no difference when preserved as hay or silage. Digestion coefficients from wilted silage were lower, however, than from direct cut silage DM (0.47 vs. 0.51; p = 0.05).