Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2012
Publication Date: 7/2/2012
Citation: Hales, K.E., Freetly, H.C. 2012. Effects of roughage concentration in dry-rolled corn-based diets containing wet distillers grains with solubles on performance and carcass characteristics of finishing beef steers [abstract]. Journal of Animal Science. 90(Suppl. 3):432.
Technical Abstract: Distillers grains and distillers solubles are by-products of grain fermentation used to produce ethanol and contain relatively high concentrations of NDF and ADF compared with other grains and concentrates it replaces in feedlot diets. Typical finishing diets in the U. S. contain 8.3 and 9.0% roughage in the summer and winter months, respectively. Therefore, it is plausible that the dietary concentration of roughage can be altered when distillers grains are included in feedlot diets. The effects of roughage concentration in dry-rolled corn-based diets containing wet distillers grains with solubles (WDGS) were evaluated in MARC II steers (n = 128, initial BW = 339 kg) using Calan gates. Diets consisted of 25% WDGS and the balance being dry-rolled corn and coarsely ground alfalfa hay (AH) replacing corn at 2 (AH-2), 6 (AH-6), 10 (AH-10), and 14% (AH-14) of dietary dry matter. Daily feed offered was recorded, feed refusals were measured weekly, and BW was measured on d 0, 1, 35, 70, 105, 140, 174, and 175. At slaughter, camera data were collected. The data were analyzed using the Mixed procedure of SAS. The fixed effect of treatment was included in the model. Decreasing concentrations of AH in the finishing diet resulted in no differences in final BW (P = 0.18), but a tendency for ADG (P = 0.06) to be greater when steers were fed intermediate concentrations of AH (6 and 10%) than AH-2 and AH-14. Steers consuming AH-2 had a lower DMI (P = 0.04) than steers consuming AH-6, AH-10, or AH-14; whereas, G:F was greater for steers consuming AH-2, AH-6, and AH-10 than AH-14 (P < 0.01). Concentration of AH in the finishing diet did not affect HCW, LM area, marbling score, or the proportion of cattle grading USDA choice (P > 0.32); however, dressing percent was greater for steers fed AH-2 and AH-14 than AH-6 and AH-10 (P = 0.04). Results indicate that decreasing AH to 2% in a finishing diet based on dry-rolled corn with WDGS may not affect ADG, but does decrease DMI which results in an increased G:F.