Effects of Whole or Rolled Corn Diets on Steer Growing and Finishing Feedlot Performance

Crossbred steers (n = 192; average initial BW, 302 ± 0.52 kg) were used in a 61 d growing and 79 d finishing study to evaluate feeding whole or rolled corn in growing and finishing diets. Steers were blocked by initial BW and randomly allotted to 16 pens (12 steers/pen). The pens were assigned randomly to one of two corn treatments: whole corn (WC) or dry rolled corn (DRC). The backgrounding diets were 18% straw, 26% corn silage, 28% modified distillers grain (MDGS), 26% corn, and 2% vitamin and mineral supplement (VMS). The finishing diets were 9% straw, 12% corn silage, 26% MDGS, 51% corn, and 2% VMS. Steers were weighed individually on d 0 and approximately every 28 d through the growing and finishing phases. Steers were given an anabolic implant (36 mg estradiol from zeranol) prior to arrival at the feedlot. Steers were re-implanted with 120 mg TBA and 24 mg estradiol on d 61. Cattle were harvested at a commercial abattoir on d 140. Hot carcass weights were taken at harvest and the following carcass attributes were evaluated after a 24-h chill: 12^th rib fat depth, LM area, KPH, marbling, and USDA yield grade. Performance and carcass variables were analyzed using the GLM procedure of SAS, with pen serving as the experimental unit. Initial, 61 d and final BW were similar for both the WC and DRC treatments (P ≥ 0.64). There were no differences in growing and finishing period or overall average daily gain between treatments (P ≥ 0.22). Additionally DMI was similar (P ≥ 0.21) among treatments overall and across both the growing and finishing phases. Gain to feed was also similar (P ≥ 0.23) among corn treatments overall and across both the growing and finishing phases. All carcass characteristics were similar (P ≥ 0.71) for WC and DRC treatments. These results indicate that feeding either whole or dry rolled corn through the growing and finishing phases will result in similar animal performance and carcass characteristics.