Zinc Supplementation Forms Influenced Zinc Absorption and Accumulation in Piglets

SIMPLE SUMMARY: High levels of inorganic Zn were supplemented to meet the nutritional requirements of Zn in piglets, which results in the development of intestinal microbial resistance and environmental pollution. Previous research indicated that organic Zn sources had higher bioavailability than inorganic Zn. There is limited information on the comparison of dietary Zn source dissolved in water with other Zn supplementation forms in piglets. Therefore, the present study was designed to compare the effects of three Zn supplementation forms (Zn-Met in the feed, ZnSO(4) in the feed, and ZnSO(4) dissolved in drinking water) on growth performance, Zn accumulation, activities of Zn-containing enzymes, expression of MT, and Zn transporters in piglets. In conclusion, Zn-Met and ZnSO(4) dissolved in drinking water had higher bioavailability in piglets. ABSTRACT: The study aimed at determining the effect of different zinc (Zn) supplementation forms on Zn accumulation, activities of Zn-containing enzymes, gene expression of metallothionein (MT), and Zn transporters in piglets. Eighteen piglets were randomly divided into three groups: (a) a basal diet supplemented with 150 mg/kg Zn from Zn methionine (Zn-Met) in the feed (Zn-Met group), (b) a basal diet supplemented with 150 mg/kg Zn from Zn sulfate (ZnSO(4)) in the feed (ZnSO(4), (feed) group), and (c) a basal diet supplemented with the same dose of Zn as in ZnSO4,(feed) group but in water (ZnSO(4), (water) group). The results showed that Zn-Met added in feed and ZnSO(4) dissolved in drinking water significantly improved (p < 0.05) the Zn concentration in liver and jejunum and the apparent digestibility of Zn in comparison with the ZnSO(4) added in feed. In addition, dietary Zn supplementation as Zn-Met significantly increased (p < 0.05) the activity of alkaline phosphatase (AKP) in the jejunum of piglets in comparison with the ZnSO(4), (feed) group. Furthermore, the Zn-Met and ZnSO(4), (water) groups showed an improved total superoxide dismutase activity (T-SOD) in the ileum as compared to the ZnSO(4), (feed) group. Meanwhile, the qPCR and western blot results showed that Zn-Met and ZnSO(4) dissolved in drinking water increased the expression of MT in the jejunum in comparison with the ZnSO(4) added in the piglets’ feed. However, different Zn supplementation forms had no effect on the mRNA expressions of Zip4 and ZnT1 transporters. In conclusion, Zn-Met added in feed and ZnSO(4) dissolved in drinking water had higher bioavailability in piglets.