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 x Landrace x 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 26day 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.