LAUSR

Single-source, Angus-cross steers (n = 204; 249 ± 23 kg) were utilized to determine the effect of supplemental vitamin (VE; ROVIMIX E-50 Adsorbate, DSM Nutritional Products) on performance and immunity during feedlot receiving. Seven days post-arrival, steers were blocked by BW and weaning protocol (pre-weaned or not) into pens (n = 5 or 6 steers/pen) and pens randomly assigned to VE treatments: no supplemental VE (CON), VE at 25 IU/kg DM (LOW; average 151 IU·steer-1·d-1), 500 IU·steer-1·d-1 (MED), or 1000 IU·steer-1·d-1 (HIGH). Steers were weighed on d -1, 0, 14, 26 and 27. On d 6, steers were boostered with Bovi-Shield Gold (One Shot, Zoetis). Serum collected from one steer per pen was analyzed for Se and α-tocopherol (d -1 and 26) and Bovine Viral Diarrhea Virus (BVDV) type 1 and 2 antibody titers (d 6, 14, 26). Data were analyzed using Proc Mixed of SAS with pen as the experimental unit (n = 9 pens/treatment), the fixed effects of treatment and block, and the random effect of pen. Linear, quadratic and cubic contrast statements were constructed. Serum Se and α-tocopherol concentrations from d -1 and titers from d 6 (prior to vaccination) served as covariates. From d 14 to 27, ADG and G:F quadratically increased (P ≤ 0.02), with MED being greatest; VE did not affect d 0 to 14 or overall trial performance (P ≥ 0.14). Day 26 BVDV type 1 antibody titers and α-tocopherol concentrations (2.7, 3.4, 4.6, and 5.8 mg/L for CON, LOW, MED, and HIGH, respectively) linearly increased due to VE (P ≤ 0.04). Increasing supplemental VE improved circulating VE concentrations and antibody response to a booster vaccine. Performance benefits were observed when VE was supplemented at 500 IU·steer-1·d-1, the dose recommended by NASEM (2016) for stressed cattle.