Abstract
Nano-porous zinc oxide (NP-ZnO), characterized by its large specific surface area and high porosity, has been considered a suitable alternative to high-dose zinc oxide (ZnO). However, its effects on piglets subjected to enterotoxigenic Escherichia coli (ETEC) challenge remain unknown. This study was conducted to explore the protective effect of NP-ZnO on reducing diarrhea incidence and the underlying mechanisms in weaned pigs following ETEC challenge. Thirty-six 21-d-old, weaned piglets (6.62 ± 0.23 kg) were randomly assigned to four treatments. Piglets in the control (CON) and ETEC challenged groups were fed the basal diet, while others were fed basal diet containing either ZnO (2000 mg/kg) or NP-ZnO (1500 mg/kg) for 14 d, before oral administration of ETEC or culture medium. During the initial 1-14 d, both NP-ZnO and ZnO improved growth performance and the apparent total tract digestibility (ATTD) of dry matter, crude protein, gross energy, ether extract and ash (P < 0.01), while reducing diarrhea incidence (P < 0.05). Following ETEC challenge, NP-ZnO and ZnO inhibited the reduction of average daily feed intake, average daily gain and the ratio of gain to feed (P < 0.01) induced by ETEC, with NP-ZnO alleviated the diarrhea rate induced by ETEC (P < 0.05). In addition, both NP-ZnO and ZnO reversed ETEC-induced decrease in IL-10 mRNA expression and increase in Caspase-1 mRNA expression (P < 0.05). NP-ZnO improved antioxidant status in ETEC-challenged piglets by elevating GSH-Px, T-SOD, and T-AOC levels and reducing serum DAO concentrations (P < 0.05). Moreover, NP-ZnO upregulated mRNA expression of jejunal Nrf2 and Occludin, and colonic AQP3 (P < 0.05). Collectively, NP-ZnO improved growth performance, reduced diarrhea, and alleviated ETEC-induced oxidative stress and intestinal damage, suggesting that NP-ZnO is an efficient alternative to conventional ZnO in weaned piglets.