As the ostomy bag has been removed, it will be difficult to obtain stool samples for 72 hours. Therefore, we will only measure zinc urine excretion, not secretion and will not be able to assess copper balance at this time point. The infant will receive 1 mg Zn67 orally mixed into one of the infant's morning feedings on the study day. In addition, the infant will receive 0.1 mg Zn70 intravenously. A small collection of blood (2 mL) will also be taken at the time of the isotope infusion. This blood will be tested for zinc, copper, and ceruloplasmin levels. One spot urine sample will be obtained at 96 hours after the first isotope is received.