Corn and sudangrass intercropped with Kura clover for Midwestern pastures

Abstract

AbstractWarm‐season annual grasses have potential to increase the productivity of Midwestern grazing systems in mid‐summer when cool‐season species production slumps. This research investigated forage nutritive value and steer performance for two warm‐season annual grasses, corn (Zea mays L.) and sudangrass [Sorghum bicolor (L.) Moench.], intercropped with Kura clover (Trifolium abiguum M. Bieb.). Mixtures were rotationally grazed with Holstein (Bos taurus; 242 kg, n = 180 yr−1) steers from 2014 to 2016. Corn–Kura clover (C‐KC) and sudangrass–Kura clover (SG‐KC) were grazed for 24 d from mid‐July to mid‐August and SG‐KC regrowth was grazed an additional 24 d from mid‐Aug to mid‐September. Forage harvested was greater (P < .05) for SG‐KC (3442 ± 223 kg ha−1) than C‐KC (2426 ± 193 kg ha−1). A mixture × year effect (P = .03) was detected for in vitro true digestibility (IVTD) and all forage nutritive variables had year effects (P < .01). Crude protein did not differ between treatments (P = .30), neutral detergent fiber (NDF) was lower (P < .01), and IVTD and NDF digestibility were higher (P < .05) in C‐KC. A mixture × year effect (P < .05) existed because heat stress suppressed average daily gain in the C‐KC grazing session in 2016. Steer gain per hectare was greater for SG‐KC (P < .01), with 318 kg ha−1 and 195 kg ha−1 for SG‐KC and C‐KC, respectively. Despite greater forage nutritive value in C‐KC, SG‐KC resulted in greater animal gain per hectare due to regrowth potential after first grazing.