Zellmer, Chris2025-02-142025-02-142024-09https://hdl.handle.net/11299/269971University of Minnesota Ph.D. dissertation. September 2024. Major: Animal Sciences. Advisors: Ryan Cox, Alfredo DiCostanzo. 1 computer file (PDF); viii, 73 pages.Two experiments were conducted in 2019 and 2020 at the Beef Research and Education Center feedlot near Rosemount, MN. Experiment one evaluated the effects of intake management, ad-libitum (AD-LIB) or restricted (REST), and dietary energy concentration, high (HI) or moderate (MOD), fed to steers (n = 139) during a 49-d backgrounding period in a 2 × 2 factorial design and finished on a common-finishing diet. Dietary treatments were 1) 1.43 NEg Mcal/kg ad-libitum (HI AD-LIB); 2) 1.43 NEg Mcal/kg fed to gain 1.13 kg/day (HI REST); 3) 1.31 NEg Mcal/kg ad-libitum (MOD AD-LIB); 4) 1.31 NEg Mcal/kg fed to gain 1.13 kg/day (MOD REST). Steers fed REST treatments exhibited reduced DMI in the backgrounding and finishing periods, and overall (P < 0.0001). Daily gain was reduced during the backgrounding phase and overall (P < 0.0001), but similar during the finishing phase. Carcass traits were poorer for cattle on REST treatments (P ≤ 0.04). There were no effects of intake management on live performance in the backgrounding or finishing periods or overall (P ≥ 0.15). Quality grade was improved for steers fed HI treatments (P = 0.04), but there were no other impacts on carcass characteristics (P ≥ 0.44). There were interactions for BF (P = 0.04) and HCW (P = 0.06). In experiment two incremental increases in the ratio (HMC-RAT) of high-moisture (HMC) to dry-rolled corn (DRC) were fed to steers (n = 115) during the finishing phase to investigate the effects of HMC-RAT on feedlot performance and carcass characteristics. Dietary treatments consisted of 1) 20:80 HMC:DRC; 2) 40:60 HMC:DRC; 3) 60:40 HMC:DRC; 4) 80:20 HMC:DRC with similar concentrations of corn silage, dried distiller grains with solubles, and supplement. Ratio of HMC:DRC did not impact feedlot performance. Yield grade was greatest for steers fed a 40:60, intermediate for 20:80, and least for 60:40 and 80:20 HMC:DRC, respectively (P = 0.04). Other carcass traits were similar across dietary treatments. Feeding AD-LIB during the backgrounding period improved live performance and carcass characteristics. Ratio of HMC:DRC did not exhibit effects on finishing performance or a majority of carcass traits. Key Words: cattle, backgrounding, finishing, feedlot, programmed gain, intake management, high-moisture corn, dry-rolled cornenbackgroundingcattlefeedlotfinishinghigh-moisture cornintake managementThesis or Dissertation