Effects of corn processing method on performance and carcass characteristics of finishing beef cattle fed diets containing sorghum wet distillers grain plus solubles
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Two experiments were conducted to study the effects of corn processing method and inclusion of sorghum wet distillers grains plus solubles (SWDGS) in beef cattle finishing diets. In Experiment 1, 160 crossbred steers (BW = 397.6 kg) were used to evaluate the effects of corn processing method on performance and carcass characteristics in the following diets : (1) a dry-rolled corn (DRC)-based diet with no inclusion of SWDGS (DRC-0); (2) a DRC-based diet with inclusion of 15% (DM basis) SWDGS (DRC-15); (3) a steam-flaked corn (SFC)-based diet with 0% SWDGS (SFC-0); and (4) a SFC-based diet with 15% SWDGS (SFC-15). No interactions (P ¡Ý 0.20) were noted for performance and carcass characteristics, except for marbling score and % of carcasses grading USDA Choice or greater. Results showed lower (P < 0.01) G:F with DRC- than for SFC-based diets. Steers fed SFC-based diets had greater fat thickness at the 12th rib (P = 0.03), greater yield grade (P = 0.02), and a smaller LM area (P = 0.08) than steers fed the DRC-based diets. Inclusion of 15% SWDGS resulted in lower G:F (P < 0.01) than for diets without SWDGS. In addition, steers fed SWDGS had lower HCW (P = 0.01) and dressing percent (P = 0.03) than those fed no SWDGS. In Experiment 2, feed samples from Experiment 1 were used to evaluate rate of in vitro gas production, in vitro dry matter disappearance (IVDMD), and hydrogen sulfide (H2S) concentrations in gas using different types of in vitro fermentation systems. No significant interactions were noted for IVDMD, H2S production, and for mathematically fitted gas production parameters, except for the predicted maximum value of gas production. The SFC-based diets had greater IVDMD (P = 0.01), area under the gas production curve (P < 0.02), and rate (k) of gas production (P < 0.02) than DRC-based diets. Inclusion of 15% SWDGS in the substrates decreased IVDMD (P < 0.01), AUC (P = 0.03), and k value (P = 0.04) vs. 0% SWDGS. No differences in H2S production (P = 0.15) or lag time (P = 0.51) were found at 15% SWDGS. Results of both experiments suggest that the response to 15% (DM basis) SWDGS in finishing diets was not affected by corn processing method. The inclusion of 15% SWDGS decreased G:F and fermentation measurements to approximately the same extent as replacing all the SFC in the diet with DRC.