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The objective of this study was to investigate the effects of dietary zinc (Zn) source and level of supplementation on performance, egg quality, blood parameters, and egg yolk Zn content in laying hens from 28 to 36 weeks of age. Two hundred laying hens (Hy-Line W-36) were weighed individually and placed randomly in cages with five treatments, five replicates of 8 birds in each using a 2×2+1 factorial arrangement. Treatments consisted of a control diet (cornsoybean meal as a basal diet without Zn supplementation) and the diet supplemented with 80 and 120 mg of Zn/kg, added as either Zinc-sulfate (ZnSulf) or Zn-methionine (ZnMet), respectively. Treatments did not impact on the laying hen performance. Eggshell thickness was improved (P<0.001) by ZnMet in comparison to ZnSulf. Eggshell thickness improved by increasing Zn from 80 to 120 mg/kg of the diet (P<0.05). Plasma HDL (P<0.001), alkaline phosphatase activity (P<0.05), total protein, and albumin concentrations (P<0.001) increased by ZnMet in comparison to ZnSulf supplementation. Plasma Fe, Cu, Zn, and P, and Zn contents of the egg yolk were not affected by Zn sources or levels. Plasma Ca was higher in hens receiving 120 mg/kg ZnMet/kg than other treatments (P<0.01). In conclusion, more positive effects on eggshell quality and some blood parameters were found by dietary ZnMet supplementation at 80 or 120 mg/kg diet than ZnSulf in laying hens under the conditions of this study. [ABSTRACT FROM AUTHOR]

Abstract: An experiment of 70days was conducted on 20 male lambs (6–7months of age) to determine the effects of Zn supplementation (ZnSo4 and Zn-proteinate) in a barley based diet on mineral profile, some serum and plasma metabolites and performance in lambs. Animals were randomly allotted to 4 treatments including;1) basal diet containing 22.47mg Zn/kg DM, without supplementary Zn (control); 2) basal diet+40mg Zn/kg DM as ZnSO4 (ZnSO4 40); 3) basal diet+20mg Zn/kg DM as Zn-proteinate (Zn-Pro 20), and 4) basal diet+40mg Zn/kg DM as Zn-proteinate (Zn-Pro 40). The basal diet was provided according to NRC (2007) to meet or exceed lambs requirements except Zn. Blood samples were taken on days 28, 30, 65 and 70 before morning feeding. Daily feed intake, plasma Ca and Cu and beta-carotene concentration did not differ significantly between treatments. Plasma Zn concentration, serum vitamin A concentration, alkaline phosphatase (ALP) and superoxide dismutase (SOD) activity differed significantly between control and Zn supplemented groups (P <0.05) as Zn supplementation improved these parameters. Average daily gain and feed efficiency improved with Zn supplementation (P <0.05). The results of this study show that Zn improved performance of lambs and adding 20mg Zn/kg DM to the basal diet might be sufficient to meet the Zn requirement of the lambs. [Copyright &y& Elsevier]