Fe-59 is retained from an elemental Fe-59 powder supplement without effects on (65)zinc, (47)calcium and (67)copper in young pigs

In vivo counting with the use of a germanium detector evaluated the retenti on of an elemental Fe-59 powder supplement while measuring potential intera ctions with zinc, calcium and copper. Effects of dietary iron and zinc on i n vivo retentions of Fe-59, Zn-65, Cu-67 and Ca-47 were studied in young pi gs. In Experiment 1, 4-d-old piglets fed a cereal-based diet were randomly assigned to one of four treatment groups (2 x 2 factorial arrangement, n = 5 per group). Variables were dietary iron source (either elemental iron or FeSO4, each at 100 mg iron/kg diet) and the dosage form of radioactive iron (either elemental Fe-59 powder or (FeSO4)-Fe-59). Experiment 2 (2 x 3 fact orial arrangement) was performed using two levels of iron (100 and 200 mg/k g, as elemental iron) and three levels of zinc (25, 50 and 100 mg/kg). Pigl ets were also dosed with Ca-47, Zn-65 and Cu-67; all radioisotopes were mea sured for 8 d. Apparent absorption of elemental Fe-59 powder was 13 +/- 1%, whereas 59Fe sulfate was significantly (P < 0.05) higher at 26 +/- 1%. The FeSO4 diet decreased Zn-65 retention in Experiment 1, in contrast to the e lemental iron diet, which did not have this effect in either experiment, Ap parent Zn-65 absorption averaged 44 +/- 2, 35 +/- 1 and 27 +/- 2% for the t hree levels of zinc (25, 50 and 100 mg/kg), respectively. Retention of Ca-4 7 was not affected by dietary iron or zinc; retention of Cu-67 was not affe cted by dietary iron. The data demonstrate good bioavailability of elementa l iron without effects on zinc, copper and calcium.