Inclusion Criteria:  Evidence of personally signed and dated informed consent document indicating that the infant's parent(s) have been informed of all pertinent aspects of the study Parent(s) are willing and able to fulfill the requirements of the study protocol Healthy full term (37-42 weeks gestation) infant Be between post-natal age (Date of Birth = Day 0) 7 days to 2 months Parent(s) must have independently elected, before enrollment, to formula feed  Exclusion Criteria:  Any known intolerance/allergy to cow's milk (formula-fed group only) systemic disorders (cardiac, respiratory, endocrinological, hematologic, gastointestinal, or other) conditions requireing infant feedings other than those specified in the protocol Infants must have been exclusively consuming breast milk since birth, and their parent(s) must have made the decision to continue exclusively breastfeeding until at least 4 month of age