The use of nutrient material other than mother's milk does not completely meet the needs of the baby. For example, no other nutrient material contains the antibodies required for the baby's immune system.
Cow's milk is considered to be the classic nutrient material for babies. When we compare it with mother's milk, we can better understand the superiority of the latter. In cow's milk there is a higher amount of casein than in human milk. Casein is a protein found in coagulated (sour) milk. This material breaks down into larger pieces in the stomach making digestion difficult. For this reason, cow's milk is harder to digest than mother's milk. The fact that little of this material is found in mother's milk makes the baby's digestion easier.
These two kinds of milk are also different with regard to the composition of amino acids. Due to this difference in composition, the total number of amino acids present in the plasma of a baby fed with cow's milk is greater; the level of some amino acids is too high while the level of others is too low. This has negative effects on the nervous system and, because of the higher protein content, places an extra burden on the kidneys.
Another factor that makes mother's milk different is its sugar content. In mother's milk and cow's milk there is the same kind of sugar-lactose. But the amount of lactose in human milk (L / 7g) is different from that in cow's milk (L / 4.8g). Besides, the large coagulated particles of cow's milk pass much more slowly through the small intestine. For this reason, high amounts of fluid and lactose, which are very important, are absorbed in the first section of the small intestine. Coagulated particles of mother's milk (unlike those of cow's milk) pass through the small intestine easily, and lactose and fluid reach the large intestine. In this way, a healthy intestinal structure develops. The second advantage of the great quantity of lactose found in human milk is that it ensures the synthesis of a material called "cerebroside", which plays an important role in the construction of the essential structures of the nervous system.
Despite the fact that the fat level in mother's milk and cow's milk is almost the same, the quality of those fats is different. The linoleic acid in mother's milk is the only fatty acid required in the nourishment of the baby.
Another factor that distinguishes mother's milk is the amount and proportion of the salt and minerals it contains. For example, in cow's milk the amount of calcium and phosphorus is high; but the ratio of calcium to phosphorus in cow's milk makes it difficult to digest properly. Phosphorus can combine with calcium in the digestive tract and actually prevent the absorption of calcium. Therefore, if a baby is given cow's milk in the first days of its life, the way can be opened to certain abnormalities due to a drop of the level of calcium in the blood.
Apart from this, human milk is 50% iron. Because cow's milk contains a much lower proportion of this mineral, babies fed on cow's milk can develop anaemia linked to iron deficiency.
Richness in vitamins is another factor that makes mother's milk indispensable for the baby. From the point of view of the vitamins they contain, mother's milk and cow's milk are quite different. Despite the fact that the level of vitamin A is the same, the level of vitamins E, C and K is higher in mother's milk. The amount of vitamin D in mother's milk is sufficient for the baby's needs.