Effects of different zinc sources on growth performance, antioxidant capacity and zinc storage of weaned piglets

Abstract

This study was conducted to investigate the effects of different zinc sources on growth performance, tissue and fecal mineral concentrations, antioxidant capacity and genes expression of zinc related transporters in weaned piglets. A total of 200 weaned piglets (Duroc × Landrace × Yorkshire) with average body weight (BW) of 8.55 ± 0.39 kg were allotted to control group (basal diet) and three treatment groups (basal diet supplemented with 100 mg Zn/kg as ZnSO4, 100 mg Zn/kg as Zn-Gly and 100 mg Zn/kg as Zn-Met, respectively) for 35 days. The results showed that supplementation with different Zn sources did not influence the average daily feed intake (ADFI). However, weaned piglets fed with Zn supplementation diet had lower diarrhea rate when compared with control group (P < 0.05). In Zn-Gly group, average daily weight gain (ADG) was increased significantly while the feed/gain ratio (F/G) was reduced than those fed with basal diet (P < 0.05). Compared with the control group, red blood cells (RBC), hemoglobin (Hb) and packed cell volume (PCV) in Zn-Gly group were increased significantly and the absolute lymphocytes was decreased (P < 0.05). White blood cell (WBC) and absolute basophils were decreased in Zn supplementation groups (P < 0.05). Meanwhile, the Zn concentration in liver was higher than control group (P < 0.05). In Zn-Gly group, the Zn concentration in tibia and pancreas were promoted compared with control group (P < 0.05). Fecal Zn concentration was the highest in all groups (P < 0.05). But the Zn concentration in serum, kidney and spleen in all groups had no significant differences. In addition, Zn-Gly improved total antioxidant capacity (T-AOC), alkaline phosphatase (AKP) and copper/zinc superoxide dismutase (Cu/Zn SOD) in serum and reduced the level of nitric oxide (NO) (P < 0.05). In liver, the levels of AKP, GSH-Px and T-AOC were enhanced while the levels of NO and MDA were lower when compared with control group (P < 0.05). Results of RT-qPCR showed that metallothionein (MT1) mRNA was upregulated significantly whereas the Zrt/Irt-like proteins (ZIP4) mRNA which is the iron regulatory proteins was downregulated in duodenum (P < 0.05). In jejunum, the expression of MT1 mRNA was upregulated by Zn-Gly and the ZIP4 mRNA was downregulated by ZnSO4 and Zn-Met (P < 0.05). In summary, the supplementation of different zinc sources for 35 days improved the growth performance and tissue mineral concentration in piglets. Moreover, organic zinc had better effects on antioxidant capacity and the apparent digestion rates of Zn than ZnSO4.