Zinc oxide nanoparticles improve gut health and reduce faecal zinc excretion in piglets

This study investigated the effects of zinc oxide nanoparticles (ZnO–N) on growth performance, gut health, and zinc and copper excretion in piglets. A total of 144 piglets (Duroc × Landrace × Large White, weaned at 21 days; mean initial weight 6.15 ± 0.01 kg) were assigned to six groups with six replicates of four pigs per pen for a 26-day feeding trial. The groups were: antibiotic group (basal diet + 75 mg/kg aureomycin), ZnO group (basal diet + 1,600 mg/kg zinc oxide), and four ZnO–N groups (basal diet + 200, 300, 400, or 500 mg/kg ZnO–N, respectively). No significant difference in growth performance was observed amongst the treatments. ZnO–N supplementation improved the activities of superoxide dismutase (linear or quadratic, p < 0.05), copper-zinc superoxide dismutase in the ileum (linear, p < 0.05), catalase in the jejunum and ileum (linear or quadratic, p < 0.05), total antioxidant capacity of duodenum and ileum (linear, p < 0.05), and glutathione peroxidase in the ileum (linear, p < 0.05), and reduced malondialdehyde content in the jejunum (linear, p < 0.05). As ZnO–N content was increased, the contents of jejunal IgA, interleukin (IL)-6, and IL-10 decreased (linear, p < 0.05), while IgM content increased (linear, p < 0.05). The contents of ileal IgA and IL-10 increased (linear and quadratic, p < 0.05), while the contents of IgM, IgG, and IL-6 decreased (linear or quadratic, p < 0.05). Villus height and the ratio of villus height to crypt depth in piglets fed with ZnO–N were higher than in the antibiotic group (p < 0.05). Pigs fed with 200–500 mg/kg ZnO–N showed lower contents of hepatic zinc and copper and faecal zinc than the ZnO group (p < 0.05). These results show that dietary ZnO–N enhanced intestinal antioxidant and immune capacity and intestinal morphology, particularly 500 mg/kg ZnO–N, and also that ZnO–N minimised zinc content in the liver and faeces.