Effect of zinc oxide nanoparticle supplementation in Santa Inês ewes during the transition period

Zinc oxide nanoparticles (N-ZnO) represent a promising alternative for zinc (Zn) supplementation, since their reduced size provides greater bioavailability and better integration into the body. Furthermore, this characteristic becomes particularly relevant during periods of increased metabolic stress, such as the transition phase. Thus, the objective was to evaluate the effects of N-ZnO supplementation in Santa Inês sheep during the peripartum period. Thirty-three ewes with an average body weight of 43.3 ± 2.05 kg were, distributed into three experimental groups: control group (CON), without supplementation, receiving only Cynodon spp. hay; and groups supplemented with 300 mg/animal/day of N-ZnO (40 nm) and zinc oxide microparticles (M-ZnO). The supplementation was administered orally in capsules daily from late pregnancy until weaning. The results showed no significant differences (P > 0.05) in body weight, egg count per gram of feces (EPG), and in most of the hematological, biochemical, and immunological parameters evaluated. However, differences (P < 0.05) were observed in monocyte counts and albumin levels, with higher means in the N-ZnO group, showing differences compared with the M-ZnO group, while the CON group maintained intermediate values. The N-ZnO group showed differences compared to the M-ZnO group, while the CON group maintained intermediate values. Regarding antioxidant activity, a significant effect (P < 0.05) was observed on the enzymes Superoxidase dismutase (SOD), Glutathione peroxidase (GPx), Catalase (Cat), and on the total antioxidant status (ORAC) of the sheep supplemented with N-ZnO. It is concluded that N-ZnO supplementation improved the antioxidant response, with no signs of intoxication, using a dose of 300 mg during the period of greatest oxidative stress.