This pilot study primarily aimed to compare effects of breast feeding, A1 versus A2®cow milk based formula on alimentation and gastrointestinal digestion. The impact of the study products on fecal myeloperoxidase (MPO), short-chain fatty acid (SCFA), secretory immunoglobulin A (sIgA) concentration, gastrointestinal tolerance, defecating habit and infant growth were also evaluated.

Inclusion Criteria:

• Willing to formula feeding and consume 600ml or more of IF each day;
• Have normal electrocardiograms (ECG) and blood pressure during quiet respiration.
• Agree not to take any medication, supplements, nutrition or other dairy products including acidophilus milk;
• Parent(s) or legal guardian's consent to the study and willing to comply with study procedures;
• Parent(s) or guardian of infant agrees not to enroll infant another clinical study while participating in this study;
• Fully understand the nature, objective, benefit and the potential risks and side effects of the study.

Exclusion Criteria:

• Twins, multiple birth, low birth weight children, over birth weight children or early birth children with gestational age less than 37 weeks;
• During pregnancy, the mothers had pregnancy complications or other disease that may affect the results;
• Having serious diseases that may affect study interventions, such as neonatal sepsis, pneumonia (associated with respiratory failure), heart failure and other disease;
• Having neonatal diarrhea or acute respiratory infections within 48hours before enrollment;
• Having potential metabolic diseases, chronic diseases, congenital malformations, central nervous system disorders, neuromuscular disorders or diseases affecting bone metabolism that may affect growth or the study results;
• Having taken any food containing prebiotics or probiotics tithing 15 days of enrollment;
• Body weight-to-height Z-value <-3 according to the standard of the World Health Organization (WHO);
• Receiving hormone therapy and intravenous nutrition;
• Lactose intolerance or allergic to ingredients of study product;
• Have history of faecal impaction;
• Have participated in similar dairy or probiotics-containing product's clinical trials within 3 months before the screening;
• Currently taking medicines for cardiovascular or metabolic disease ;
• Currently suffering from any gastrointestinal disorders or gastrointestinal disease , including but not limited to: irritable bowel syndrome, colitis, ulcerative colitis, celiac disease, irritable bowel syndrome(IBS);
• Had hospitalizations within 3 months before screening;
• According to investigator's judgment, current frequent users of drugs which may affect the gastrointestinal function or immune system;
• Unable to comply the study schedule.