Inclusion Criteria:
1. Written informed consent has been obtained from at least one parent (or legally acceptable representative \[LAR\])
2. Parent(s) / LAR(s) must be able to provide evidence of parental authority and identity
3. Parent(s) / LAR(s) must understand the informed consent form and other study documents
4. Parent(s) / LAR(s) are willing and able to comply with scheduled visits and the requirements of the study protocol
5. Parent(s) / LAR(s) can be contacted directly by telephone throughout the study
6. Parent(s) / LAR(s) must be able to temporarily store stool samples in a household freezer
7. Infants may be exclusively breastfed, exclusively formula-fed, or mixed fed with both breast milk and infant formula in any proportion. Parent(s) / LAR(s) must intend to maintain the infant's current mode of feeding until the end of the study period:
1. For exclusively breastfed infants: parents must intend to continue exclusive breastfeeding. As defined by the World Health Organization, exclusive breastfeeding means that the infant receives only breast milk. No other liquids or solids are given (not even water) with the exception of oral rehydration solution, or drops/syrups of vitamins, minerals, or medicines.
2. For formula-fed infants (either exclusively or mixed-fed): parent(s) / LAR(s) must intend to maintain the infant's current mode of feeding, plus:
* Parents / LAR(s) must have previously and independently decided to use formula
* Infant must be consuming and tolerating a standard cow's milk infant formula not containing probiotics at the time of enrollment
8. Infant must be healthy based on medical history and physical examination
9. Infant full-term gestational birth (born 37 weeks, 0 days through 41 weeks, 6 days of gestation)
10. Infant singleton birth
11. Infant postnatal age ≥ 14 and ≤ 28 days (date of birth = day 0)
12. Infant birth weight is appropriate for gestational age (≥ 2500 and ≤ 4500 grams)
Exclusion Criteria:
1. Infants with conditions requiring specific infant feeding regimens other than those specified in the protocol
2. Infants who have a medical condition or medical history that could increase the risk associated with study participation or interfere with the interpretation of study results, including:
1. Evidence of major congenital malformations (e.g., cleft palate, extremity malformation)
2. Suspected or documented systemic or congenital infections (e.g., human immunodeficiency virus, cytomegalovirus, syphilis)
3. Previous or ongoing antibiotic usage by the infant, except when given for prophylactic reasons (e.g., erythromycin ophthalmic ointment)
4. Immunocompromised infants and those who have a central venous catheter
5. History of admission to the Neonatal Intensive Care Unit, except for admission for jaundice phototherapy
6. Known or suspected allergy to milk (including lactose) or soy
7. Previous or ongoing severe medical or laboratory abnormality (acute or chronic) which, in the judgement of the investigator, would make the infant inappropriate for entry into the study
3. Infants who are currently receiving or who have received any probiotic supplements or infant formula containing probiotics prior to enrollment
4. Infants who are currently receiving or who have received any of the following medication(s) or supplement(s) which are known or suspected to affect fat digestion, absorption, and/or metabolism (e.g., pancreatic enzymes), stool characteristics (e.g., glycerin suppositories, bismuth-containing medications, docusate, Maltsupex, or lactulose), growth (e.g. insulin or growth hormone), microbiome-related endpoints (e.g., prebiotic supplements), or gastric acid secretion
5. Infants whose parent(s) / LAR(s) have not reached the legal age of majority (18 years old)
6. Infants who are currently or who previously participated in another interventional clinical study
7. Parent(s) / LAR(s) with family or hierarchical relationships with the research team members
