Evaluation of Warm-Season Annual Forages in Forage-Finishing Beef Production Systems.

The demand for locally grown, forage-finished beef products has increased in the last decade and has created a need for alternative forage-finishing strategies.  A three year study was conducted to evaluate four warm-season annual forages in a southeastern forage-finishing beef production system.  Forage treatments were brown midrib sorghum x sudangrass [Sorghum bicolor var. bicolor*bicolor var. sudanense; BMR], sorghum x sudangrass [SS], pearl millet [Pennisetum glaucum (L.) R.Br.; PM], or pearl millet planted with crabgrass [Digitaria sanguinalis (L.) Scop.; PMCG].  Treatments were planted at a seeding rate of 22.4, 22.4, 16.8, and 11.2 + 5.6 kg ha^-1, respectively. Sixteen pastures (0.81-ha) were assigned to one of four forage treatments in a randomized complete block design. Pastures were subdivided for rotational grazing by British-cross beef steers (n = 32; 438±49 kg).  Put and take grazing was used to maintain a forage allowance of 1600-4500 kg ha^-1.  Forage yield was measured by clipping in triplicate a 4.3-m² area with a plot harvester on day 0 and on 14 d intervals.  Hand grab samples for forage quality determination and metabolic body weights were measured on day 0 and on 34 d intervals until termination of the trial.  In 2014, DM yield was greater for BMR and SS compared to PM and PMCG at day 0 (P < 0.001; 1657, 1958, 1205, and 1297 kg h^-1, respectively) and at day 14 (P < 0.0148; 4007, 4670, 3485, and 2962 kg h^-1, respectively) while in 2015, BMR, SS and PM outperformed PMCG at day 0 (P < 0.0574; 2548, 2755, 3016, and 2039 kg h^-1, respectively).  ADG was significantly (P = 0.0032) higher for BMR (0.90 kg/d) compared to steers grazing SS and PMCG (0.68 and 0.62 kg/d, respectively) but did not differ from PM (P = 0.1472; 0.79 kg/d).  Results from 2 years of data suggest that BMR, SS, PM, and PMCG may all be used in forage-finishing beef production systems but BMR may outperform SS, PM, and PMCG on the parameters of forage yield and animal performance.