194 Evaluation of Dietary Roughage Inclusion in a Single or Two-Diet System for Backgrounding and Finishing Steers

Abstract

Abstract The objective of this experiment was to determine the influence that equal cumulative roughage inclusion in a single diet or two-diet system during a 210-d growing-finishing period has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in beef steers. Pre-conditioned beef steers (n = 46; initial shrunk [4%] BW = 281 ± 40.4 kgs) were fed once daily, and bunks were managed according to a slick bunk management system at the Ruminant Nutrition Center in Brookings, SD. Treatments included: 1) A single diet program (targeted a 1.30 Mcal/kg NEg diet fed for 210-d; 1D) or 2) two diet program (targeted a 1.21 Mcal/kg NEg diet fed for 98-d, a 1.30 Mcal/kg NEg diet fed for 14-d, and a 1.39 Mcal/kg NEg diet fed for 98-d; 2D). All steers were implanted on d 1 with a 100 mg trenbolone acetate (TBA) and 14 mg estradiol benzoate (EB) implant and re-implanted with a 200 mg TBA and 28 mg EB implant on d 112. Average daily gain tended (P = 0.06) to be 9.5% greater for 1D compared with 2D during the backgrounding portion and ADG was increased (P = 0.01) for 2D compared with 1D by 11.3% during the finishing phase of the experiment. Cumulative ADG did not differ between treatments (1.61 vs. 1.62 ± 0.046 kgs) for 1D and 2D, respectively. Cumulative observed dietary NEm and NEg did not differ (P ≥ 0.96) between treatments. There were no differences (P ≥ 0.18) detected between treatments for HCW, DP, REA, RF, USDA marbling score, KPH, yield grade, retail yield, EBF, or body weight at 28% estimated EBF. In conclusion, Northern Plains feedlot producers can feed a single growing-finishing diet to preconditioned beef steers with minimal effects on overall growth performance or carcass traits.