Effects of wet corn and sorghum distillers grain on performance carcass characteristics of finishing beef cattle and on in vitro fermentation of steam-flaked corn-based substrates
DeClerck, Jon Charles
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Two experiments were conducted to evaluate the effects of level of inclusion of wet distillers grain with solubles (WDGS; 15 and 30% of dry matter [DM]) and WDGS source (sorghum, corn, or a 50:50 blend of corn and sorghum WDGS) on performance and carcass characteristics of finishing beef cattle fed steam-flaked corn- based (SFC) diets. In Exp. 1, 224 steers (primarily British Continental breeding) were fed steam flaked corn- based (SFC) diets consisting of (DM basis): (1) SDG-15 = 15% sorghum WDGS; (2) SDG-30 = 30% sorghum WDGS; (3) CDG-15 = 15% corn WDGS; (4) CDG-30 = 30% corn WDGS; (5) BDG-15 = 15% 50:50 blend of WDGS; (6) BDG-30 = 30% 50:50 blend of WDGS; and (7) CONTROL = 0% WDGS. Seven treatments were replicated in 8 blocks, and arranged in a 2 3 + 1 factorial and were balanced for fat, with crude protein (CP) concentrations allowed to fluctuate. Decreased carcass-adjusted final BW and hot carcass weight was observed as inclusion level of WDG increased in the diet (DM basis; P 0.05). Gain-to-feed ratio (G:F) did not differ among CDG, BDG, and control treatments, but G:F was numerically less with either level of SDG than for control and decreased (P 0.05) as WDGS inclusion level increased from 15 to 30%. An interaction (P 0.05) was noted between SDG and BDG sources and WDGS level for carcass-adjusted G:F for the overall feeding period, with little difference in G:F of SDG diets as level increased from 15 to 30% but decreased G:F with BDG diets as WDGS level increased. Cattle fed control diets had greater dressing percent (0.05< P 0.10), 12th rib fat, and YG than cattle fed WDGS diets (P 0.05). In Exp. 2, the effects of inclusion of WDG (15 and 30%) and sources (CDG and SDG) on in vitro rate of gas production, DM disappearance (IVDMD), and H2S production were evaluated. Substrate treatments used for the in vitro fermentation studies were (DM basis): (1) a SFC-based diet with no WDGS; (2) a SFC-based diet with 15% CDG; (3) a SFC-based diet with 15% SDG; (4) a SFC-based diet with 30% CDG; and (5) a SFC-based diet with 30% SDG. Five treatments were arranged in a 2 2 + 1 factorial and were balanced for fat, with CP concentrations allowed to fluctuate. An increase was observed for H2S production (moles/g of fermentable DM), as inclusion level of WDGS increased from 15 to 30% of the treatment substrate (DM basis; P 0.05). Conversely, a decrease was observed for area under the curve (AUC) and IVDMD as the level of WDG inclusion increased (P 0.05). Control substrates had greater IVDMD, rate of gas production, and AUC (P 0.05) than WDGS-based substrates, and CDG-based substrates had a greater (P 0.05) rate of gas production, IVDMD, and AUC than SDG-based substrates. Results of these experiments suggest that WDGS can be included at moderate levels (up to 30% of the dietary DM) in SFC-based diets without adverse effects on performance by finishing beef steers. Nonetheless, as WDGS increased from 15 to 30%, a decrease was observed in IVDMD, which might explain the decrease in observed G:F ratio, HCW and final- adjusted BW as WDG increased from 15 to 30% of the diet of finishing beef steers.