The effect of excessive dietary calcium upon the absorption and utilization of selenium-75, molybdenum-99, copper-64 and iron-59 in swine

The objectives of this study were:

1. To determine the absorption and utilization of Selenium-75, Molybdenum-99, Copper-6H and Iron-59 when feeding excessive calcium to growing swine.

2. To further determine the distribution of the radioactive elements in the tissues of these animals.

3. To determine growth rate, feed consumption and feed efficiency when feeding excessive levels of calcium.

These isotopes were selected for this study because of their properties, which made it possible to employ the "multiple dosing technique". Se-75 and Mo-99 were used together because both are gamma emitters and Se-75 has a half-life of 120 days whereas Ho-99 has a halflife of 2.8 days. Likewise copper and iron were used simultaneously since Fe-59 has a half-life of 45.1 days and Cu-64 has a half-life of 12.8 hours and both are gamma emitters. Each of the samples could be counted twice and the short half-life isotope corrected for decay and determined by difference.