PSII-B-17 - Effect of Corn Grain Processing and Moisture Content in Finishing Diets Formulated to Meet Rumen Degradable Protein Requirements on Feedlot Cattle Performance

Abstract: Increased dietary inclusion of rapidly-fermentable carbohydrates and a great proportion of corn-derived CP may result in increased rumen degradable protein (RDP) microbial requirements and reduced RDP supply, respectively. An experiment was conducted to evaluate the effect of processing and moisture content of corn grain in finishing diets concurrently balanced to meet increased RDP requirements on feedlot cattle performance. A semi-dent corn hybrid crop was harvested and stored as dry-whole (DWC), dry-rolled (DRC), whole high-moisture (WHMC), or rolled high-moisture (RHMC) corn (89.3% DM and 32.4% moisture for dry and high-moisture corn, respectively). Four dietary treatments containing 78.8-79.0% corn grain were arranged by adding (DM basis) 0.15, 0.20, 0.0, or 0.0% of urea to DWC, DRC, WHMC, or RHMC-based diets, respectively, to meet RDP requirements, which were measured in previous experiments using the same corn hybrid as in the present experiment. Angus steers (n = 144; 356 ± 2.7 kg initial BW) were group-housed in 24 pens, fed once daily from d 1 to 86, and held off feed and water for 16 h to record initial and final BW. Data were analyzed as a randomized complete block (6) design. Rate of BW gain and HCW increased and DMI decreased (P ≤ 0.02) from dry and whole to moist and rolled corn-fed steers (Table 1). Consequently, steers fed the RHMC-based and 0%-urea diet were finished at heavier BW and were more efficient (P ≤ 0.02) converting feed into BW and carcass compared with steers fed any of the other diets. Feeding high-moisture compared with dry corn led to improved cattle performance and might reduce urea-derived costs. The convenience of using RHMC instead of WHMC may rely upon the balance between improved animal performance and increased feed costs associated with corn processing.