The supplements of zinc oxide and arginine are known to improve growth in weanling piglets, however, the mechanism of action is not well understood. Arginine is an essential precursor for the synthesis of nitric oxide (NO). Increased production and concentration of NO is known to cause Zn2+ release in endothelial cells and enhance antioxidant activity. In this study it was measured the antioxidant status and inflammatory response in 48 weanling castrated male piglets fed diets supplemented with or without zinc oxide (2,500 mg Zn oxide per kg) and arginine (1%). The animals (20 days of age) were injected with lipopolysaccharide (100 μg/kg) on day 5. Half of them received another injection on day 12. Blood samples were taken just before and 6, 24 and 48 h after injection and the mucosa lining the ileum was recovered following euthanizing on days 7 and 14.
Zinc supplementation increased the reduced and total glutathione (GSH) (reduced and total) during days 5 to 7 and arginine decreased oxidized GSH measured on days 5 and 12 and the ratio of total antioxidant capacity to total oxidative status during days 12 to 14. Zinc decreased plasma malondialdehyde measured on days 5 and 12 and serum haptoglobin measured on day 12 and increased both metallothionein-1 expression and total antioxidant capacity measured in the ileal mucosa on day 14. Tumour necrosis factor α concentration decreased from days 5 to 12.
This study shows that supplementing the post-weaning diet with zinc reduced plasma lipid oxidation and the haptoglobin concentration, and arginine supplementation did not modify these effects. Both supplements had inconsistent effects on inflammatory and oxidative parameters in response to inflammation by lipopolysaccharide. Nevertheless, it appears that zinc modifies GSH metabolism and arginine could negatively affect the antioxidant status of piglets with a sensitized immune system. The level of arginine in a piglet feed should be carefully selected in order to avoid possible negative effects on antioxidant status during the post-weaning period.
Bergeron, N., Robert, C., and Guay, F. (2017). Feed supplementation with arginine and zinc on antioxidant status and inflammatory response in challenged weanling piglets. Animal Nutrition, 3(3), 236-246. https://doi.org/10.1016/j.aninu.2017.06.009