Effects of graded levels of cupric citrate on growth performance, antioxidant status, serum lipid metabolites and immunity, and tissue residues of trace elements in weaned pigs

Objective: The goal of this study was to investigate the effects of cupric citrate (CuCit) on growth performance, antioxidant indices, serum lipid metabolites, serum immune indices, and tissue residues of copper (Cu), zinc, and iron in weaned pigs. Methods: A total of 180 weaned pigs ($Duroc{\times}Landrace{\times}Large$ White) with an average body weight of $8.98{\pm}1.21kg$ were randomly assigned to a corn-soybean meal control ration, or 4 similar rations with 30, 60, 120, or 240 mg/kg Cu as CuCit. All diets contained 10 mg/kg Cu as cupric sulfate from the vitamin-mineral premix. The experiment was divided into two phases: 0 to 14 d (phase 1) and 15 to 28 d (phase 2). Results: Average daily gain (ADG; linearly, p<0.01) and average daily feed intake (ADFI; linearly and quadratically, p<0.05) were affected by an increase in CuCit during phase 2. Overall period, ADG (p<0.05) and ADFI (p<0.01) were linearly increased with increasing dietary levels of CuCit. Serum malondialdehyde concentrations (p<0.05) and glutathione peroxidase activity (p<0.01) linearly decreased and increased respectively with an increase in CuCit. Serum levels of Cu-Zn superoxide dismutase were linearly affected with an increase in CuCit (p<0.01). Hepatic malondialdehyde levels decreased with an increase in CuCit (linearly and quadratically, p<0.01). Serum total cholesterol concentrations were quadratically affected (p<0.05) and decreased in pigs fed Cu as CuCit at 60 and 120 mg/kg and increased in pigs fed 240 mg/kg Cu as CuCit. Serum high-density lipoprotein concentrations were linearly affected with an increase in CuCit (p<0.01). Serum $IL-1{\beta}$ levels were quadratically affected (p<0.05) by dietary treatment. Compared with other treatments, 240 mg/kg Cu from CuCit quadratically increased hepatic (p<0.01) and renal (p<0.05) Cu concentrations, and quadratically decreased hepatic and renal iron concentrations (p<0.05). Conclusion: Cu administered in the form of CuCit at a dosage range of 30 to 60 mg/kg, effectively enhanced the growth performance and antioxidant status of weaned pigs.