Why is it advised that infants are fed mother's milk?
I have heard that mother's milk is preferred over other baby foods, because it contains immunoglobulins (secretory IgA), and other essential nutrients. But why is mother's milk so special? Any mammalian milk, such as the widely available cow's milk, should presumably have a similar composition as human milk? What makes mother's milk in specific so healthy? Could the mere act of breastfeeding, in itself, lend to some beneficial outcome?