Human milk is species specific to the human infant, just as goat milk is species specific to goats. The fat and the protein content of human milk is designed for mammals that require close contact and frequent feedings. Breastmilk digests in about 90 minutes, thus the baby wants/needs to feed about every 90-120 minutes. This is perfectly normal. When the baby is sleepy and feeding infrequently or mother 'puts the baby on a schedule', the baby does not take in enough milk and then the mother doesn't make enough mlk. Milk production is based on supply and demand.
Human milk is only 10% nutrition. The remaining 90% is designed to build, support and protect every cell and every system in the body. When you break it down this way, it begins to make more sense as to why it is so critical that a baby receive human milk-if not from its own mother then from a milk donor.
An incredible aspect of human milk is that it matches 50% of the baby's genetic material.
Learn more about Whey Proteins and Phospholipids in Breastmilk.