Kinetics of 65Zn in Sheep Supplemented with Micro- and Nanoparticles of Zinc Oxide.

Using nanotechnology in zinc supplementation may increase efficiency, reducing offered amounts and, therefore, allowing for lower cost and minimized environmental damage due to Zn contamination. This study aims to evaluate the kinetics of zinc, derived from micro- and nanometric zinc oxide, by radiolabeling this mineral through neutron activation. Eight Santa Ines ewes, around 10 months old and 23.6 ± 2.0 kg of body weight, were split into two treatments. After adaptation, they were transferred to metabolism evaluation cages, receiving capsules containing 50 mg of 65ZnO (with average 54.85 kBq of 65Zn), micro- or nanometric, on a single oral dose. After the capsules' ingestion, collections of blood samples were made (0.25h, 0.5h, 1h, 2h, 6h, 14h, 24h, and every 24h thereafter), whereas feces and urine collections were made daily through the tenth day, when the animals were euthanized, and their tissues and gastrointestinal contents collected for 65Zn counts and Zn measurement. The nanometric 65ZnO treatment presented a biological half-life 12h longer than the micrometric 65ZnO, although without statistical difference. The nanometric 65ZnO also had higher recovery rates in feces throughout the experiment (p < 0.0001). Generally, the 65Zn distribution in the tissues was similar, with the spleen being the only exception, showing higher counts in the micrometric 65ZnO group (p < 0.05). In conclusion, our results suggest that ZnO nanoparticles may be as efficient as its micrometric counterpart, although further studies are needed to evaluate the differences found in the spleen, large intestine counts, and biological half-life.