ALLAH RECOUNTS HIS BLESSINGS TO MAN....

In the Holy Quran, when Allah recounts His blessings to man, he mentions 

the cow.

Verily in cattle there is a lesson for you. We give you to drink of what is inside their bodies, coming from between the intestines and the blood, a milk pure and pleasant for those who drink it. (an-Nahl, 16:66)

The food that is eaten by the cow is digested in its intestines. From here the blood carries the nourishment to the rest of the body, including the mammary glands where the milk is produced.

Modern science tells us that the processes responsible for the production of milk begin when the contents of the intestine are brought together with the blood. And indeed, this is how the Holy Quran has explained it too.