Effects of zinc oxide nanoparticle supplementation in young sheep naturally infected with gastrointestinal nematodes

The experiment aimed to evaluate the effects of daily supplementation with 150 mg of ZnO-NP on performance, hematological and immunological responses of lambs naturally infected with GIN under grazing conditions. Given the field-based approach adopted, the study was designed as an exploratory trial to generate preliminary evidence and hypotheses for future controlled experiments, acknowledging that individual feed intake was not measured and, therefore, the effect of ZnO-NP cannot be fully isolated from variations in voluntary concentrate intake. Each animal of one group (n = 14) was daily supplemented for 127 days with a capsule containing 150 mg of ZnO-NP in powder (40 nm), while a control group (n = 13) was kept without receiving Zn supplementation. Animals supplemented with Zn showed higher PCV and TPP values in the most critical period of infection, around day 70 of the trial, indicating increased resilience against GIN infections. Precisely during this period, animals that received Zn showed the highest values of blood eosinophils and Immunoglobulin G (IgG)-anti-Haemonchus. There was a tendency for a difference between groups in mean total body weight gain (P = 0.06), where the group supplemented with zinc oxide obtained the highest means. In conclusion, daily supplementation with 150 mg of ZnO-NP was associated with increased eosinophil counts and a tendency toward greater body weight gain in young sheep naturally infected with GIN.