Effects of water soluble zinc on growth performance, immune response, and tissue zinc transporters in nursery pigs

Abstract

Regardless of adding pharmacological levels of dietary ZnO and CuSO4, supplementing water soluble Zn amino acid complex (ZnAAC) via drinking water can offer excellent Zn bioavailability to support growth and immune function of nursery pigs. In the first experiment, effects of LPS injection on the immune response and tissue Zn transporter over 24-h following challenge were evaluated. Data revealed that rectal temperature and serum TNF-a increased (P < 0.05) within 3-h following LPS. While serum Zn and Cu concentrations decreased after injection until h 6 and h 12 (P < 0.01), respectively. Serum C-reactive protein (CRP) linearly increased over time (P = 0.10). Upregulations of hepatic IL-6, ZIP14, and MT-1 gene expressions were strongly correlated (P </= 0.0017) and detected within 3-h (P < 0.0001) after LPS. Duodenal ZIP4 and MT-1 genes were upregulated (P < 0.05) at h 12 and 24, respectively. In the second experiment, pigs drinking titrated levels of water soluble ZnAAC (0, 20, 40, 80, and 160 mg Zn/L water) throughout a 42-d nursery period improved ADG (P < 0.05) and G:F (P </= 0.05) when supplemented up to 80 mg Zn/L water. Estimation of optimal ZnAAC doses for ADG and G:F using non-linear broken-line models were 74 and 70 mg Zn/L, respectively. In the third experiment, the same ZnAAC treatments were supplemented to pigs with an addition of a single LPS challenge and data collection at h 0, 3, and 12 following LPS. Data reported that pigs drinking titrated levels of ZnAAC had lower serum CRP (P = 0.04) at baseline, and mitigated febrile response by decreasing rectal temperature (P = 0.005) and serum TNF-a (P = 0.02) at h 3 following LPS when supplemented up to 80 mg Zn/L water. LPS injection decreased serum Zn and Cu concentrations of all pigs (P < 0.0001). Hepatic IL-6, ZIP14, and MT-1 gene expressions were upregulated and correlated (P </= 0.0001), while only duodenal IL-6 (P </= 0.0001) was upregulated at h 3. Results of these experiments indicated that pigs drinking water soluble ZnAAC improved growth performance and mitigated febrile response under hepatic Zn homeostasis during inflammation.