186 Hormone content of anabolic implants differentially affects plasma and liver trace mineral concentrations
Abstract Forty-eight commercial Angus steers (327 ± 25 kg) were utilized to determine effects of varying implant hormone composition on liver and plasma trace mineral concentrations. Implant (IMP) treatments (n = 12/treatment) included: no implant (CON), estradiol (E2; Compudose; 25.7 mg estradiol; Elanco Animal Health; Greenfield, IN), trenbolone acetate (TBA; Finaplix H; 200 mg trenbolone acetate; Merck Animal Health; Madison, NJ), and a combination of estradiol and trenbolone acetate (ETBA Revalor-S; 24 mg estradiol + 120 mg trenbolone acetate; Merck Animal Health). Cattle were fed forage-based step up rations throughout the sampling period. Plasma samples were collected on d 0, 2, 10 and 30, with liver biopsies collected on d 2 and 10. Data were analyzed with ProcMixed of SAS with fixed effect of IMP. Contrast statements for each treatment vs CON were developed. Plasma trace mineral analysis utilized repeated measures (repeated effect = day). No IMP × Day effects (P ≥ 0.18) on plasma trace mineral were observed. Day 2 liver Zn and Cu and d 10 liver Mn were lesser (P ≤ 0.04) for TBA implanted steers than CON and d 2 liver Mn tended to be lesser (P = 0.06). The Mn response may reflect changes in protein metabolism due to TBA. However, E2 and ETBA tended to have greater (P ≤ 0.07) d 10 liver Fe concentrations than CON while plasma Fe was unaffected (P ≥ 0.75) by E2, TBA, or ETBA. Both d 2 liver and plasma Zn were lesser for ETBA than CON (P ≤ 0.04) likely driven by the TBA in the implant. Implant contrasts did not affect (P ≥ 0.13) other plasma or liver trace mineral concentrations. These data indicate implant strategies, and thus hormones differentially influence trace mineral metabolism in feedlot steers, which may have implications for diet formulation.