Evaluation of five C4 forage grasses in the tall Fescue Belt

Across much of the eastern United States, tall fescue [TF; Schedonorus arundinaceus (Schreb.) Dumort.], a cool-season (i.e., C-3) perennial grass, is the primary forage for pasture systems, thereby leaving producers vulnerable to reduced summer forage production and drought. Warm-season (i.e., C-4) forages can complement existing production systems by supplementing summer forage production and drought resiliency. Therefore, our objective was to compare five, C-4 forage options in a grazing trial: switchgrass (SW; Panicum virgatum L.), eastern gamagrass (EG; Tripsacum dactyloides L.), a big bluestem (Andropogon gerardiiVitman) and indiangrass (Sorghastrum nutans L. Nash) blend (BBI), bermudagrass (BG; Cynodon dactylon L. Pers), and crabgrass (CG; Digitaria sanguinalis L. Scop.). Research was conducted 2014-2016 at two locations in Tennessee. Weaned beef heifers (237-242 kg initial weight) grazed 1.2-ha pastures with three replications per species and location. Average daily gains (kg d(-1)) (0.62 [BBI], 0.41 [BG], 0.44 [CG], 0.42 [EG], 0.51 [SW]), grazing days (d ha(-1)) (412 [BBI], 459 [BG], 455 [CG], 664 [EG], 617 [SW]), and total gain (kg ha(-1)) (259 [BBI], 186 [BG], 200 [CG], 276 [EG], 315 [SW]) all varied among forages (P <.001). Similarly, forage nutritive values differed (P <.001) among forages: season-long crude protein ranged from 94 (BG) to 115 (CG and EG) g kg(-1), neutral detergent fiber (NDF), 601 (CG)-680 (SW) g kg(-1), and acid detergent fiber (ADF) 379 (BG)-417 (EG) g kg(-1). These forage options should be evaluated in the context of TF pastures to establish a broader understanding of their contribution within an overall forage system.

Automated summary

This study compared the performance of five C-4 forage options in a grazing trial, showing variations in average daily gains, grazing days, total gains, and forage nutritive values among the different forages. Therefore, incorporating these forage options in tall fescue pastures can provide more choices for producers.