Zinc and copper status in ewes supplemented with sulfate- and amino acid-complexed forms of zinc and copper

Thirty g-yr-old Targhee ewes were randomly allotted to one of five suppleme ntal treatments to evaluate supplementation effects on liver and fecal Zn a nd Cu concentrations and serum alkaline phosphatase activity: 1) control, 2 ) Zn complex, 3) Zn and Cu (ZnCu) complex, 4) Zn sulfate, and 5) ZnCu sulfa tes. Supplements were administered daily in gelatin capsules for 56 d. Live r biopsies and serum samples were collected every 14 d starting on d 0. Sup plemental Zn and Cu levels were formulated to provide 90 mg/kg Zn and 10 mg /kg Cu, respectively, on a daily dry matter intake basis. Form (complex vs sulfate) x type (Zn vs ZnCu) interactions were not detected (P > 0.35). The refore, contrast statements were used to make the following treatment compa risons: 1) control vs supplement, 2) Zn vs ZnCu, and 3) complex vs sulfate. Ewe BW at the end of the study (P = 0.09) and ewe BW change from beginning to end of the study (P = 0.07) were greater for supplemented than control ewes. Body weight and BW change did not differ between sulfate and complex (P > 0.39) or Zn- and ZnCu- (P > 0.40) supplemented ewes. Liver Cu concentr ations did not differ (P = 0.41) between control and supplemented ewes. Liv er Cu concentrations were higher (P < 0.10) for ewes supplemented with ZnCu than Zn and complex than sulfate forms of supplement. Liver Zn concentrati on tended (P = 0.13) to be higher in ZnCu than Zn-supplemented ewes. Liver and fecal Zn concentration were higher (P < 0.06) in ewes fed complex than sulfate supplements. However, serum alkaline phosphatase activity tended (P = 0.12) to be greater in ewes fed sulfate than complex supplements. Supple menting mature ewes with complexed minerals resulted in higher concentratio ns of Zn and Cu in the liver. In addition, supplemental Cu tended to increa se concentrations of Zn in the livers of ewes; however, high levels of supp lemental Zn did not negatively impact liver Cu concentrations.