Determination of the Efficacy of Titrated Levels of Water Soluble Zinc Amino Acid Complex on Immune Response of Nursery Pigs

Zinc has been studied for its effects to modulate the immune response, but few studies have investigated the effects of supplementing zinc via water. To evaluate the efficacy of a water soluble zinc amino acid complex “Zinpro LQ” (Zinpro Corporation, Eden Prairie, MN), two hundred eighty crossbred pigs (5.6 kg BW; PIC 337) were randomly allotted to four water treatments (7 pens/treatment; 10 pigs/pen). The water treatments were 0, 20, 40 and 80 mg of Zn/L of water. Pigs were fed a common diet with added Zn as ZnO or Cu as CuSO₄ during each dietary phase: Phase 1 (2,500 mg Zn/kg; from d 1-7), Phase 2 (1,750 mg Zn/kg; from d 7-14), Phase 3 (200 mg Cu/kg; from d 14-21), and Phase 4 (200 mg Cu/kg; from d 21-42). Diets were corn-soybean meal based with no added medications. At d 23 (11.3 kg BW), pigs were challenged by IM injection of lipopolysaccharide (12 µg/kg BW). Prior to injection at h 0 and post-injection at h 3 and 12, BW and rectal temperature (RT) were measured and blood collected from two pigs per pen. At h 0 and 3, no differences (P > 0.05) were observed for BW, RT, TNF-α, cortisol, or serum zinc and copper concentration. At h 0 and 3, decreased C-reactive protein (CRP; quadratic, P < 0.05; 82.71, 61.18, 49.37, and 61.24 µg/mL; 104.55, 79.76, 63.27, and 83.25 µg/mL) was observed. At h 12, there were no differences (P > 0.05) in BW, TNF-α, cortisol, CRP or serum zinc concentration; however, decreased serum copper concentration (quadratic, P < 0.0001; 2.89, 2.24, 2.13, and 2.40 mg/L), and increased RT (quadratic, P < 0.10; 39.2, 39.6, 39.8, and 39.4℃) were noted. From h 3-12, RT decreased (quadratic, P < 0.05; -1.50, -0.99, -0.83, and -1.21℃), CRP increased (quadratic, P < 0.10), and serum copper concentration decreased with increasing zinc intake (quadratic, P < 0.05; 0.37, -0.17, -0.12, and 0.08 mg/L). From h 0-12, serum zinc (quadratic, P < 0.10; -0.05, -0.18, -0.14, and -0.04 mg/L) and copper (quadratic, P < 0.0001; -0.05, -0.71, -0.73, and -0.46 mg/L) concentrations decreased. In conclusion, supplementing nursery pig drinking water with Zinpro LQ, in the presence of dietary pharmacological levels of zinc and copper under acute immune challenge, did not alleviate stress or cytokine concentration, but resulted in a lower acute phase protein concentration. Moreover, serum copper concentration decreased with increasing zinc intake.