PSI-29 Behavior of ZnO micro and nanoparticles in ewes using radiolabeled 65Zn.

Abstract By using 65ZnO radiolabeled through neutron activation, this study aimed to investigate the dynamics of zinc in ewes supplemented with micro and nanoscale zinc oxide. For this, eight Santa Ines ewe, with 10 months old and weighing 23.6 ± 2.0 kg, were used, divided into two equally sized treatments. One group supplied with the capsules containing 50 mg of 65ZnO 40 nm nanoparticles, and the other with the capsules containing 50 mg of 65ZnO micro particles. Following the adaption period, the animals were moved to metabolism cages and had received single-dose oral capsules (with average 54.85 kBq of 65Zn), with micro or nanoscale zinc oxide. Once the capsules were ingested, blood samples were collected at specific time points (0.25h, 0.5h, 1h, 2h, 6h, 14h, 24h, and every 24 hours thereafter), while feces and urine samples were collected daily for ten days. At the end of this period, the animals were euthanized to collect tissues and gastrointestinal contents for zinc concentration analysis. The nanoscale 65ZnO exhibited a biological half-life that was 12 hours longer compared to the microscale 65ZnO, although no significant difference was observed between treatments (P >0.05), suggesting a longer retention time in the animal’s body. Regarding fecal excretion, sheep receiving the nanoscale treatment showed a higher recovery rate, possibly associated with faster intestinal transit. Overall, 65Zn distribution across tissues was similar between treatments, except for the spleen, which accumulated higher levels of 65Zn in the microscale treatment (P< 0.05). Although further studies evaluating additional parameters are needed, these findings suggest that nanoscale ZnO could potentially replace its microscale counterpart in continuous zinc supplementation.