Abstract Thirty-six wether lambs (33.49 ± 2.81 kg) were used to determine the relative bioavailability of supplemental potentiated zinc oxide (HiZox) compared to zinc sulfate (ZnSO4) and resulting effects on zinc (Zn) retention, nutrient digestibility, and nitrogen (N) balance. Wethers were sorted by body weight (BW) into 3 blocks and stagger started to accommodate the available facilities. Upon arrival, wethers were randomly assigned to treatments. On day -25 (relative to collection period start), they were housed in group pens in Kildee Hall (Ames, IA) and began a low-Zn diet that would be fed for the entirety of the study. Wethers were moved to individual crates on day -10, where they were allotted 5 days of acclamation before dietary treatments began on day -5. Zinc treatments were fed as a top-dressing using ground corn as a carrier: 1) Control (CON) – no additional Zn supplementation, 2) HiZox (HIZOX) – 40 mg of supplemented Zn from a potentiated Zn oxide, and 3) Zinc sulfate (ZS) – 40 mg of supplemented Zn from ZnSO4. Day 1 began a 5-day total collection period of fecal and urine that was utilized for determination of Zn and N retention, as well as dry matter (DM) and organic matter (OM) digestibility. Blood was collected at the end of the depletion phase, during the metabolism period, and following the metabolism period, to measure circulating plasma Zn concentrations. Data was analyzed using the mixed procedure of SAS 9.4 (SAS Institute, Cary, NC). Contrasts were developed to compare CON vs. ZINC (HIZOX and ZS together) and the two Zn sources (HIZOX vs. ZS). Significance was declared at P ≤ 0.05 and tendencies at 0.05 P ≤ 0.10. No differences were observed amongst dietary treatments for DM or OM intake, output, or N digestibility (P ≥ 0.24). Zinc intake, fecal and urinary output, retention (mg/d and percent of intake), and apparent absorption were greater for ZINC compared with CON (P ≤ 0.01) but did not differ between Zn sources (P ≥ 0.44). The inclusion of supplemental Zn improved N apparent absorption (P = 0.02), however, no differences were observed between Zn sources (P = 0.25). In these experimental conditions, the data indicates that the potentiated Zn oxide has a similar relative bioavailability compared to Zn sulfate and elicited similar effects on diet digestibility and N utilization. Additionally, this experiment further demonstrates a link between Zn supplementation and N metabolism where Zn supplementation improved N apparent absorption when compared to non-supplemented animals.
Dahlback et al. (Wed,) studied this question.