Effects of dietary zinc oxide levels on the metabolism of zinc and copper in weaned pigs.

This study compared different dietary zinc oxide (ZnO) levels on zinc (Zn) and copper (Cu) metabolism in weaned pigs. One hundred twenty weaned piglets (7.96 ± 1.17 kg; 21 days of age) were used in a completely randomized 3x4 factorial design composed with three levels of dietary ZnO at 100 (100Zn), 1000 (1000Zn), or 3000 mg/kg (3000Zn) and four ages at slaughter at 21 (d21), 23 (d23), 35 (d35), and 42 days (d42). Dietary Cu levels were constant at 130 mg/kg. Serum, jejunum, liver, and kidney levels of Zn and Cu as well as mRNA abundance of genes related to Zn and Cu metabolism were analyzed. Zinc levels were greatest in 3000Zn piglets from d35 in all tissues (P ≤ 0.01). In 3000Zn piglets, mRNA expression of ZIP4 was reduced in jejunum whereas ZnT1 and MT3 were stimulated in jejunum and liver and MT1 in kidney (P ≤ 0.04) from d35. Copper levels were greatest in jejunum (P = 0.06) and kidney (P ≤ 0.01; d35 and 42 only) and lowest in liver and serum (P ≤ 0.01) of 3000Zn piglets. In conclusion, the treatment containing 3000 mg ZnO/kg triggered Zn homeostatic mechanisms in weaned pigs and impaired Cu metabolism through high enterocyte and kidney Cu sequestration.