Evaluation of warm-season annual forages in forage-finishing beef cattle systems in the southeast
Harmon, Deidre Danielle
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A three year trial was conducted to evaluate the performance of sorghum x sudangrass [Sorghum bicolor var. bicolor*bicolor var. sudanense (SS)], brown-midrib sorghum x sudangrass (BMR), pearl millet [Pennisetum glaucum (L.) R.Br.; (PM)], and pearl millet planted with crabgrass [Digitaria sanguinalis (L.) Scop.; (PMCG)] in a Southeastern forage-finishing beef production system. In a randomized complete block design, 16 pastures (0.81-ha) were assigned to one of four forage treatments and were subdivided for rotational grazing. British-cross beef steers (n = 32; 3 yr average: 429±22 kg) grazed for 70, 63 and 56 days in 2014, 2015 and 2016, respectively. Forage DM yield was least (P < 0.01) for PMCG at the initiation of the grazing trial, while BMR was greater (P < 0.01) than SS at week 6. Higher stocking densities were maintained on SS than PM and PMCG (P < 0.01) at days 0, 6, 13 and 20 in 2014 and PMCG (P < 0.01) on days 0, 6, 13, and 20 in 2015. Stocking densities of BMR was greater (P < 0.01) than PM and PMCG on day 0, 6, and 13 in 2014. Sorghum x sudangrass forage systems produced greater (P < 0.12) total gains per unit of land than PM in 2014 and 2015. Forage treatment did not affect (P > 0.17) total gain, total ADG, or BW at any time point. No differences (P > 0.05) in forage treatments were observed for carcass characteristics associated with yield grade, quality grade, proximate analysis or variables associated with the break-even analysis. Additionally, a study was conducted to help producers identify superior varieties of sorghum x sudangrass (SS), pearl millet (PM), and forage sorghum [Sorghum bicolor (L.) Moench; (FS)] that consistently performed well. Differences found among varieties indicate that SS, PM, and FS should be selected based on tested yield performance. Cattle performed similarly on all forage treatments indicating that SS, BMR, PM, and PMCG may be used interchangeably. Furthermore, break-even analysis of animal production indicated that utilizing these warm-season annual forages in forage-finishing beef systems has the potential to be a profitable enterprise in the Southeast.