Manganese dioxide nanozyme alleviates PEDV GIIc-associated growth retardation in neonatal piglets by improving antioxidant status, intestinal morphology, and manganese homeostasis

IntroductionPorcine epidemic diarrhea virus (PEDV) infection threatens swine production, and growth retardation in neonatal piglets born to infected sows requires practical intervention. This study evaluated the effects of oral manganese dioxide (MnO2) nanozyme supplementation on growth and physiological indices in these piglets.MethodsIn this study, 16 litters from PEDV GIIc-infected sows were assigned to four treatment groups according to body condition and PEDV RT-qPCR Ct value, with four litters from uninfected sows used as the negative control (NC). From 3 d of age to 21 d of age, piglets from PEDV-infected sows received oral MnO2 nanozyme at different concentrations every other day.ResultsCompared with NC group, PEDV-positive control (PC) group had lower average daily gain and jejunal villus height (P < 0.05), decreased serum CAT activity and serum GSH concentration, reduced jejunal GSH concentration, altered manganese transporter expression in the duodenum, and increased hepatic manganese accumulation. In piglets, oral MnO2 nanozyme restored average daily gain to normal levels, improved jejunal villus height, and maintained GSH concentrations in serum, jejunum, and liver at levels not different from NC. MnO2 nanozyme administration also increased duodenal DMT1 expression, decreased hepatic expression of transporters such as ZIP8, tended to increase duodenal manganese content, reduced hepatic manganese-transporter expression relative to the PC group, and alleviated hepatic manganese accumulation. In rectal fecal samples from piglets, MnO2 nanozyme increased the relative abundance of beneficial bacterial genera, including Prevotella and Bifidobacterium.DiscussionOral MnO2 nanozyme supplementation was associated with alleviation of PEDV GIIc-associated growth retardation and changes in intestinal morphology, antioxidant status, and manganese-related indices. The 5 mg/L group showed a favorable growth response at the lowest tested concentration. Baseline body-weight differences should be considered when interpreting these findings, and further controlled studies are needed to establish the underlying mechanisms and optimal administration regimen.