Corn And Sudangrass Intercropped With Kura Clover For Midwestern Pastures

Warm-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 x 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 x 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.