PSXII-16 - Intercropped Sorghum Sudan Grass and Cowpea for Improved Summer Pasture

Abstract: Pastures in the southeastern United States are dominated primarily by warm season perennials such as bermudagrass which can be low in energy. Assessment of stocker cattle performance on bermudagrass pastures overseeded with alternative warm-season forages, such as sorghum sudan grass and cowpea, are scarce. A study was conducted during the summer of 2021 with crossbred steers (n = 72; 305 ± 2.8 kg initial BW) to investigate growth performance when grazing sorghum sudan grass and sorghum sudan grass intercropped with cowpea as alternatives to bermudagrass. The experiment was a randomized complete block design with 3 treatments and 3 replicates (2 ha each) per treatment. Treatments were bermudagrass (Cynodon dactylon (L.) Pers) (CON), CON overseeded with brown mid-rib sorghum sudan grass (Sorghum bicolor L.) (SS), and SS with cowpeas (Vigna unguiculata (L.) Walp) (SSCP) planted in alternate planting passes. Forage samples were collected from 3, 0.25m² quadrats placed randomly in the next available paddock just prior to grazing. The SSCP pastures had 3 additional randomly placed quadrats, 3 in SS and 3 in CP. Forage crude protein and neutral detergent fiber (NDF) did not differ (P >0.96 and 0.19, respectively) among treatments and averaged 9.1% and 65.6%. Pre-grazing forage mass was greater in SS and SSCP (P< 0.01) averaging 4,925, 3,460, and 1,590, in SS, SSCP, and CON, respectively. Animal gains were 1.04 in SSCP and 0.96 in SS, greater than 0.78 in CON (P< 0.01). Grazing days were greatest (P< 0.01) in CON (91 d) followed by SS (68 d), with the fewest grazing days in SSCP (60 d). Despite differences in grazing days, gain per ha, did not differ (P=0.39) among treatments, and averaged 261 kg/ha. Although SSCP and SS had fewer grazing days, gain per ha were similar among treatments due to greater ADG on SS and SSCP pastures.