Sorghum-sudangrass intercropped with cowpea improved pasture for stocker cattle in the mid-south

Abstract

Objective

The objective of this study was to evaluate forage production and nutrient composition and stocker cattle performance on mixed bermudagrass, sorghum-sudangrass, and sorghum-sudangrass-cowpeas pastures.

Materials and Methods

In summers of 2021 and 2022, 144 steers (8 per experimental unit) were assigned to 1 of 3 grazing treatments (2.02 ha each): mixed bermudagrass (MB), mixed bermudagrass overseeded with sorghum-sudangrass (SS), or mixed bermudagrass overseeded with sorghum-sudangrass and cowpea (SSCW), in a randomized complete block design with 3 replications each.

Results and Discussion

Forage mass was greater in SS than MB in August 2021 and September of both years, whereas SSCW forage mass was only greater than MB in September 2022. Neutral detergent fiber was lower for SS in September 2021 and lower for SS and SSCW in July and August 2022 compared with MB. Across years and months, cowpea proportion averaged only 12.4%. Timing of N fertilization caused differences in CP among mixtures, although CP was greater in SSCW than SS in August and September 2021. Average daily gain was greater in SS and SSCW in both years (1 kg/d for SS and SSCW, and 0.8 kg/d for MB). Gain per hectare had a year × treatment interaction, with similar gain per hectare in 2021 and greater gain per hectare in SS compared with MB in 2022.

Implications and Applications

Greater available forage mass in SS in August and September may fill gaps in MB systems while also improving ADG, even under moisture-limited conditions. However, when planting was delayed, SS and SSCW provided fewer grazing days than MB and, despite the increased ADG, could not compensate, and gain per hectare was similar among pasture treatments.