Why hindus consider the cow as a sacred animal?

Indian society in ancient times was primarily an agrarian society. Cow milk was used for children and in some cases replaced mother’s milk. Bulls were used to plough the fields. Cow therefore was an important part of every household. So there is little surprise that in a culture where everything in nature is considered as manifestation of God, an important animal like cow was (and still is) considered sacred and became part of Hindu mythology and religion

MORE ANSWERS ARE WELCOME!