Effects of annual small grain–brassica forage mixtures during the last 70 days of the forage-finishing period on: I. Forage production, beef steer performance, and carcass characteristics

Our objective was to determine the effects of grazing annual forage mixtures on forage, animal, and carcass performance of steers compared with cool-season perennial pasture during the finishing period. Red Angus–influenced steers (n = 24/year over 3 yr) were randomly assigned to 1 of 3 forage treatments: mixed pasture (control; MIX); 2-species small grain–brassica mixture (simple, SIMP); or 5-species small grain–brassica mixture (complex, COMP). Steers grazed their respective treatment for 64, 76, and 70 d in 2014 (yr 1), 2015 (yr 2), and 2016 (yr 3), respectively. Initial and final fasted BW were measured. Carcass data were collected 48 h postmortem. Forage biomass (kg of DM/ha) was greater (P = 0.02) for SIMP (5,909) and COMP (5,984) than for MIX (4,000). There was a treatment-by-year interaction for most of the forage chemical composition components, with higher quality forage observed for SIMP, COMP, or both. Final BW and overall ADG were greater (P < 0.01) for steers grazing MIX (518 kg and 1.16 kg/d) than for those grazing COMP (504 kg and 0.97 kg/d), which were greater than for those grazing SIMP (496 kg and 0.85 kg/d). However, total gain (kg/ha) was lower (P < 0.001) for MIX (99.9) than SIMP (138.3) and was greatest for COMP (167.1). Hot carcass weight was greater (P < 0.01) for COMP (+9%) than SIMP and MIX in yr 1, and no differences were observed in yr 2 and yr 3. Dressing percentage was greater (P < 0.01) for carcasses from steers grazing COMP compared with SIMP, which were both greater than MIX. Annual forage mixtures of SIMP and COMP can provide considerably greater amounts of DM later in the grazing season and support greater gain per hectare. Steers grazing these mixtures have similar or greater hot carcass weight compared with traditional cool-season perennial mixed pasture.