Effects of feeding condensed distiller's solubles and crude glycerin alone or in combination on finishing beef cattle performance, carcass characteristics, and in vitro fermentation.

Two experiments were conducted to evaluate the effects of feeding condensed distiller's solubles (DS) and crude glycerin alone or in combination on performance of finishing beef cattle and in vitro fermentation. In both experiments, dietary treatments consisted of a steam-flaked corn-based diet with 0% DS or crude glycerin (CON), 10% DS (CDS), 10% crude glycerin (GLY), or a combination of 5% DS and 5% crude glycerin (C+G) included on a DM basis. All treatment diets contained 15% (DM basis) wet distiller's grains plus solubles. In Exp. 1, crossbred steers ( = 256; 322 ± 15 kg initial BW) were used in a randomized complete block finishing trial. Growth performance and gain efficiency were not different ( > 0.10) across all treatments. Treatment had no effect ( > 0.10) on carcass weight, marbling score, yield grade, LM area, or percent grading USDA choice. In Exp. 2, ruminal fluid was collected from 2 ruminally cannulated steers to evaluate in vitro fermentation characteristics. No differences ( = 0.43) were observed for DM disappearance across all treatments. The GLY and C+G treatments had decreased ( = 0.02 and = 0.05, respectively) NDF disappearance (NDFD), whereas the CDS treatment tended to have decreased ( = 0.06) NDFD compared with CON. Concentrations of NH decreased ( < 0.04) with GLY and C+G treatments compared with CON. Total gas production decreased ( < 0.01) for the C+G treatment compared with other treatments. The CDS treatment had increased ( < 0.02) total VFA compared with the CON or C+G treatments. Treatments had no effect ( > 0.17) on concentrations of acetate, propionate, and butyrate, but valerate concentrations were the greatest ( < 0.04) for the CON treatment. Concentrations of isobutyrate increased ( < 0.05) for the CON and C+G treatments compared with the GLY treatment and tended to increase ( < 0.10) compared with the CDS treatment. Including DS or glycerin in the substrates decreased ( < 0.08) isovalerate compared with CON. Feeding additional byproducts such as DS and crude glycerin alone or in combination in a finishing diet did not alter live animal performance or carcass characteristics; however, feeding a combination of the 2 byproducts may alter in vitro fermentation.