RELATIVE BIOAVAILABILITY OF SUPPLEMENTAL INORGANIC ZINC SOURCES FOR CHICKS

Three experiments were conducted to investigate the relative bioavaila bility of reagent-grade (RG) and feed grade (FG) Zn sources for l-d-ol d broiler chicks. In Exp. 1, 13 treatments included a basal corn-soybe an meal diet (63 ppm Zn) of the basal diet supplemented with 400, 800, or 1,200 ppm Zn from; RG sulfate, basic carbonate, oxide, or metal an d fed for 20 d. Using multiple regression slope ratios with Zn sulfate set at 100%, bioavailability estimates were 78, 77, and 46% for carbo nate, oxide, and metal, respectively. In Exp. 2, chicks were allotted randomly to 16 treatments that included a basal corn-soybean meal diet (75 ppm Zn) or basal diet supplemented with 300, 600, or 900 ppm Zn a s either RG sulfate, FG sulfate-ii, FG sulfate-B, FG oxide-A, or FG ox ide-B and fed for 21 d. Multiple linear regression slope ratios gave r elative estimates of 99, 81, 78, and 54% for sulfate-A, sulfate-B, oxi de-A, and oxide-B sources, respectively, with RG sulfate set at 100%. In Exp. 3, chicks were fed a basal corn-soybean meal diet (35 ppm Zn) or the basal diet supplemented with 40, 80, or 120 ppm Zn from RG Zn s ulfate, FG sulfate, or FG oxide and fed for 20 d. Multiple regression slope ratios with RG sulfate set at 100% gave relative bioavailability estimates of 94 and 74% for the FG sulfate and oxide, respectively. B ioavailability estimates were similar when Zn was supplemented to diet s at high or low concentrations.