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J. L. Cox, K. Hales, K. M. Ulmer, R. J. Rasby, S. D. Shackelford, H. C. Freetly, M. E. Drewnoski, 357 Two-year study: Effect of backgrounding system on growing and finishing performance and carcass characteristics of beef steers, Journal of Animal Science, Volume 95, Issue suppl_2, March 2017, Page 174, https://doi.org/10.2527/asasmw.2017.357
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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/calf of distiller's (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 in yr 1 and 291 kg ± 4.8 in yr 2) and assigned to treatment and replicate (4 replicates 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 distiller's grains with solubles (WDGS), and 4% supplement (DM basis). The CRD and OBF calves grazed for 65 d and then were fed the grower ration for 27 d, whereas the DGR calves were fed the grower ration for 53 d. During backgrounding, the ADG of DGR calves (1.48 kg/d) was greater (P < 0.01) than that of both OBF calves (1.05 kg/d) and CRD calves (0.87 kg/d), and ADG of OBF calves was greater (P < 0.01) than that of CRD calves. At the start of finishing, BW of OBF calves (381 kg) was greater (P < 0.01) than that of DGR calves (361 kg) and CRD calves (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 calves (0.167 and 0.156, respectively) than for OBF calves (0.156 and 0.149, respectively) in both years and greater (P < 0.01) than that of CRD calves in yr 1 (0.155) but was not different (P = 0.13) in yr 2 (0.151). At harvest, HCW of OBF calves (401 kg) was greatest (P < 0.01) whereas that of CRD calves (393 kg) was intermediate and that of DGR calves (391 kg) was least. Both 12th-rib fat (P = 0.89) and calculated YG (P = 0.39) did not differ among treatments. Marbling was greater (P = 0.01) for DGR calves (429) than for CRD calves (414), whereas that of OBF calves (424) was not different from that of DGR (P = 0.30) or CRD calves (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 did not differ from calves fed a corn silage–based ration during the growing phase.
