Abstract
By extending the grazing season and lowering the ecological imprint of conventional row-crop farming systems, grazing cool-season cover crops provide a sustainable solution to increase cattle production in the Deep South. The aim of this study was to investigate the impact of different cover crop mixtures in rotations of cotton (Gossypium hirsutum) and peanuts (Arachis hypogaea) over a two-year period. The trial included 18 paddocks planted with either oat (Avena sativa; ‘Coker’), oat + crimson clover (Trifolium incarnatum; ‘Dixie’), or oat + crimson clover + brassica (Brassica rapa; ‘Purple Top’). These paddocks were randomly allocated to either grazed or ungrazed treatments (n = 3). Yearling beef steers (266 ± 44.7 kg BW) were managed under a put-and-take grazing system to maintain a forage allowance of 1 kg of DM per kilogram of BW. Biweekly forage samples were taken to assess biomass, species composition, and nutritional content. Grazing occurred over a 65-d period from January 17 to March 22, 2023, and approximately 70 d during the 2024 period, from February 1 to April 18, 2024. Steer weights were measured at both the beginning and end of the grazing period to calculate average daily gain. Results showed no interaction between treatments and grazing (P = 0.46) nor differences among treatments (P = 0.67) for yield parameters in the first year. However, grazed paddocks exhibited greater crude protein concentrations than ungrazed paddocks (P = 0.02). There was no effect of year or grazing treatment on neutral detergent fiber (P = 0.13), nor were there any interactions between year and treatment (P = 0.81). Additionally, there was no difference for year, grazing, and treatment interactions (P = 0.5319). Forage yield in 2024 was lower than in 2023, with grazed paddocks exhibiting reduced yields in the second year. These results suggest that cover crops can provide sufficient yield and nutritive value to support grazing steers during the cool season.