An alternative ZnO with large specific surface area: Preparation, physicochemical characterization and effects on growth performance, diarrhea, zinc metabolism and gut barrier function of weaning piglets

High-dose ZnO is widely used to prevent diarrhea and promote growth of weaning piglets, which has led to serious problems of animal toxicity, bacterial resistance and environmental pollution. In this study, a novel alternative ZnO (AZO) was prepared and its physicochemical properties were characterized. Animal experiments were further con-ducted to evaluate the effects of the ZnO forms, the dose of AZO and the combinations with AZO on the growth per-formance, diarrhea, zinc metabolism and gut barrier function of weaning piglets. The results showed that the AZO, compared with ordinary ZnO (OZO), nano ZnO (NZO) and porous ZnO (PZO), had the largest surface area and reduced the release of Zn2+ into the gastric fluid. AZO showed better antibacterial activity on Escherichia coli K88, Staphylococ-cus aureus and Salmonella enteritidis but lower cytotoxicity on porcine intestinal epithelial cells. Animal experiments suggested that low-dose AZO, NZO and PZO (300 mg/kg) improved growth performance and reduced diarrhea in weaning piglets as well as high-dose OZO (3000 mg/kg). Notably, low-dose AZO had the lowest diarrhea incidence. Additionally, low-dose AZO in combination with probiotics improved digestibility and digestive enzyme activities. Low-dose AZO in combination with probiotics also upregulated the expression of the intestinal zinc transporter pro-teins ZIP4 and DMT1, increased zinc bioavailability, reduced faecal zinc emissions, and avoided zinc overload in the liver and oxidative damage caused by high-dose ZnO. Moreover, low-dose AZO in combination with probiotics im-proved the gut barrier function of weaning piglets by promoting the expression of tight junction proteins, mucins and antimicrobial peptides and increasing gut microbiota diversity and beneficial Lactobacillus. This study proposed

Automated summary

In this study, a novel alternative ZnO (AZO) was developed and its effects on the growth performance, diarrhea, zinc metabolism, and gut barrier function of weaning piglets were evaluated. The results showed that low-dose AZO improved growth performance and reduced diarrhea, and when combined with probiotics, it enhanced digestibility, gut barrier function, and gut microbiota diversity. Additionally, AZO had unique physicochemical properties compared to other forms of ZnO, with a larger surface area and lower toxicity.