264 Evaluation of Precision Feeding on Production Efficiency Responses in Finishing Beef Cattle

Abstract

Abstract Charolais-Angus cross steers (n = 128; initial shrunk BW = 505 ± 32.1 kg; n = 16 pens; 8 replicate pens/treatment) were used in a 94-day finishing phase experiment to evaluate animal growth performance outcomes, efficiency measures, and carcass characteristics when varying degrees of ingredient inclusion tolerances were imposed. Treatments included: 1) Normal feeding with 0.454 kg tolerance for all ingredients (FXD) and 2) Variable inclusion strategy where each ingredient was randomly increased or decreased but the targeted as-fed quantity for the daily delivery was met (VAR). All steers were fed twice daily with all bunks managed using a slick bunk approach. Ractopamine HCl was fed (300 mg per head daily) for the final 28 d. Individual BW measures were captured at processing approximately every 35 d. Diets consisted of high-moisture corn (HMC), dry-rolled corn (DRC), dried distillers grains plus solubles (DDGS), liquid supplement (LS), and grass hay (GH) for the first 40 days of the finishing period. Days 41-94 diets consisted of DRC, LS, DDS, GH, and corn silage (CRNSIL). Ingredient inclusions were randomized by assigning independently a random integer to HMC, GH and DDGS with each integer corresponding to the deviation from targeted inclusions; LS inclusion was held constant. As-fed inclusion rates varied from formulated targets by -20, -15, -10, -5, 0, +5, +10, +15, or +20%. DRC or CRNSIL was adjusted so that the targeted as-fed amount of the diet was delivered each day. Data were analyzed using the GLIMMIX procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC) with pen as the experimental unit and block as random effect. VAR steers had increased (P ≤ 0.01) dry matter intake (DMI) and reduced (P ≤ 0.02) kg of gain to kg of feed (G:F). However, no differences (P = 0.75) were detected between treatments for ADG. In addition, net energy for maintenance and gain was decreased (P ≤ 0.01) in VAR. Carcass characteristics for both treatments showed no significance (P ≥ 0.38) in HCW, dressing percentage, rib eye area, rib fat, KPH, yield grade, retail yield, empty body fat, or body weight at 28% estimated EBF. A tendency for increased USDA marbling score (P > 0.08) was noted in VAR. Under the conditions of this experiment, randomly altering ingredient proportions did impact growth performance and efficiency measures. However, despite the difference in growth efficiency carcass characteristics were not impacted.