The mammary glands of the female undergo differentiation during pregnancy and starts producing milk towards the end of pregnancy by the process called lactation.

The milk produced during the initial few days of lactation is called colostrum which contains antibody $(\operatorname{Ig} \mathrm{A})$.

Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby.

The synthesis of milk in mammary gland is done by prolaction of anterior pituitary.