PSV-15 - Effects of dietary zinc/copper ratio on the systemic and cellular antioxidant response and mitochondrial energy metabolism in weaned piglets

Abstract: This study examined the effects of different dietary zinc/copper ratios as zinc oxide (ZnO) and copper sulfate (CuSO₄) on intestinal and liver mitochondria ATP synthesis and the cellular and systemic redox balance in weaned pigs. One hundred and sixty weaned piglets were randomly allocated to the experimental diets containing low (L) and high (H) Zn (100 and 3000 mg/kg) and Cu levels (6 and 130 mg/kg). Piglets were slaughter at day 21, 28, 35 or 42 and blood, jejunum mucosa and liver samples were collected. Liver mitochondria Zn and Cu concentrations and mitochondria respiration, and plasma antioxidant and inflammation markers were analyzed. In the jejunum mucosa, the oxygen consumption rate (OCR) for maximal respiration tended to be higher for HZn at day 35 (P = 0.06) whereas HCu piglets had higher OCR for maximal respiration (day 42; P = 0.05) and tended to have higher OCR for ATP production at day 35 and 42 (P ≤ 0.09). Jejunum mitochondria Cu/Zn-superoxide dismutase (SOD1) activity was higher in HZn groups at day 42 (P < 0.01) and there was not effect on jejunum mitochondrial glutathione peroxidase (GPx) (P > 0.14). Piglets fed HZn had greater Zn concentrations in liver mitochondria (P < 0.01) whereas Cu concentration were higher for HCu at day 28 (P = 0.02) and for LZnHCu at day 42 (P < 0.01). The OCR for maximal respiration in liver was lowest for HZnLCu at day 35 (P = 0.01) whereas LZnLCu piglets tended to have higher OCR for ATP production at day 42 (P = 0.08). Hepatic ATP concentrations were lower for HZn groups at day 28, 35 and 42 (P ≤ 0.01). Hepatic mitochondria SOD1 activity was lower for HZn piglets at day 28, 35 and 42 (P ≤ 0.04), GPX activity was higher for HCu groups at day 28 (P = 0.01) and there was no effect of treatment for liver protein carbonyl concentrations (P > 0.13). At the systemic level, there was not treatment effect on plasma carbonyl and 8-OHG concentrations as well as on plasma SOD activity (P ≥ 0.15) whereas GPX activity was highest for HZnLCu at day 28 and 35 and lower for HCu piglets at day 42 (P ≤ 0.04). Plasma concentrations of IL1-β and TNF-α were higher for HZn piglets at day 28 (P ≤ 0.03). In conclusion, high dietary Cu increased ATP synthesis at the jejunum mucosa level. High dietary Zn promoted a unbalance in Zn and Cu homeostasis in liver mitochondria, impaired mitochondria respiration and ATP synthesis and reduced SOD activity. At the systemic level, high dietary Zn levels stimulated inflammation. Low dietary Zn/Cu ratios may promote better systemic and cellular antioxidant response and mitochondrial energy metabolism.