Effects of Various Combinations of Zinc and Copper Sources on Mitochondrial Zinc and Copper Status and Respiration in Different Tissues of Post-weaned Piglets

This study evaluated the effects of dietary inorganic (I) and organic (O) zinc (Zn) and copper (Cu) sources combinations on their intestinal and hepatic mitochondrial concentrations and mitochondrial respiration in post-weaned piglets. One hundred and ten piglets (d21; 7.79 ± 0.49 kg) were randomly assigned to a 2 × 2 factorial arrangement of Zn (ZnO or Zn proteinate) and Cu ( CuSO4 or Cu-amino acid complex) sources at 300 and 130 mg/kg, respectively (IZnICu, OZnOCu, IZnOCu, and OZnICu) and an additional inorganic group supplemented with supranutritional levels of both trace minerals (HZnHCu; 3,000 and 250 mg/kg of Zn and Cu, respectively). Tissue samples were collected at days 21, 28 and 35, for the analysis of mitochondrial Zn and Cu concentrations as well as mitochondrial respiration in jejunum and liver. Statistical analyses compared the different combinations of Zn and Cu versus the high level of these trace minerals in addition to a 2x2 factorial contrast between the different combinations of Zn and Cu at each time point. In jejunal mitochondria, HZnHCu piglets had greater Zn and Cu concentrations at d28 and 35 (P ≤ 0.08) whereas no differences were detected between the combination of sources, except for lowest mitochondria Zn concentrations in OZnICu at d28 (P = 0.06). Liver mitochondrial Cu concentrations were greater (P < 0.01) in HZnHCu but no difference was detect for Zn concentrations (P ≥ 0.26). At d28, IZn groups had higher Zn concentrations than OZn (P = 0.05). No treatment effect was detected on jejunum cytochrome c oxidase activity (P ≥ 0.51) whereas in liver the activity was highest for OZnOCu piglets (P = 0.05). Basal oxygen consumption rate (OCR) in jejunal mitochondria was highest for IZnICu at d35 (P = 0.04), while in liver it tended to be higher in OCu than ICu piglets at d35 (P = 0.08). Jejunal mitochondrial OCR for proton leak was highest in IZnICu (P = 0.04) whereas no difference was detected in liver (P ≥ 0.14). The jejunum OCR for ATP production tended to be higher at d35 for HZnHCu (P = 0.08). Among the combinations of Zn and Cu sources, IZnOCu had the lowest OCR for ATP production in jejunum (d35; P = 0.03) whereas no effect was detected in liver (P ≥ 0.18). Jejunal OCR for maximal respiration tended to be lowest for IZnOCu at d35 (P = 0.10) whereas no effect was detected in liver (P ≥ 0.23). In conclusion, HZnHCu supplementation impacted the homeostasis of Zn and Cu in jejunal and liver mitochondria. In jejunal mitochondria, a lower mitochondrial energy efficiency was detected in IZnOCu piglets, whereas those fed IZnICu were the most efficient. In the liver, OCu supplementation appered to reduce mitochondrial efficiency.