Comparative A1 vs A2 Formula and Breast Feeding on Alimentation and Gastrointestinal Digestion for the Infant

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.