|COX, J - University Of Nebraska|
|ULMER, K - University Of Nebraska|
|RASBY, R - University Of Nebraska|
|DREWNOSKI, MARY - University Of Nebraska|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 12/22/2016
Publication Date: 3/31/2017
Citation: Cox, J.L., Hales, K.E., Ulmer, K.M., Rasby, R.J., Shackelford, S.D., Freetly, H.C., Drewnoski, M.E. 2017. Two-year study: Effect of backgrounding system on growing and finishing performance and carcass characteristics of beef steers [abstract]. Journal of Animal Science. 95(Supplement 2):174. doi:10.2527/asasmw.2017.357.
Technical Abstract: A 2-yr study evaluated growing and finishing performance, as well as carcass characteristics of spring-born calves backgrounded using 1 of 3 treatments: 1) corn residue grazing supplemented 6 d/wk with 2.77 kg DM/head of distillers (CRD), 2) oat-brassica forage grazing (OBF), or 3) drylotting on a grower ration (DGR). Steers (n = 715) were stratified by BW (278 kg ± 1.2 yr 1 and 291 kg ± 4.8 yr 2) and assigned to treatment and replicate (n = 4 reps each year). Oat-brassica forage consisted of 27.9% turnip, 13.6% radish, and 58.5% oats (DM basis). The grower ration contained 51% corn silage, 25% alfalfa hay, 20% wet distillers grains with solubles (WDGS), and 4% supplement (DM basis). The CRD and OBF grazed for 65 d and then were fed the grower ration for 27 d, while DGR were fed grower ration for 53 d. During backgrounding, the ADG of DGR (1.48 kg/d) was greater (P < 0.01) than both OBF (1.05 kg/d) and CRD (0.87 kg/d), and ADG of OBF was greater (P < 0.01) than CRD. At the start of finishing, BW of OBF (381 kg) was greater (P < 0.01) than DGR (361 kg) and CRD (366 kg). The finishing diet was fed for 160 d across all treatments and consisted of 55.8% dry-rolled corn, 32.3% WDGS, 8.7% corn silage, and 3.2% supplement. Finishing G:F was greater (P < 0.01) for DGR (0.167 and 0.156, respectively) than OBF (0.156 and 0.149, respectively) in both years and greater (P < 0.01) than CRD in year 1 (0.155), but not different (P = 0.13) in year 2 (0.151). At harvest, HCW of OBF (401 kg) was greatest (P < 0.01) while CRD (393 kg) was intermediate, and DGR (391 kg) was least. Both 12th rib fat (P = 0.89) and calculated YG (P = 0.39) didn’t differ among treatments. Marbling was greater (P = 0.01) for DGR (429) than CRD (414), while OBF (424) was not different from DGR (P = 0.30) or CRD (P = 0.10). Although calves drylotted and fed a grower ration had greater ADG, the lower cost of gain associated with the grazing systems make these backgrounding methods economically competitive. Additionally, based on marbling, the quality of carcasses produced by grazing oat-brassica forage didn’t differ from calves fed a corn silage based ration during the growing phase.