The Vedic People, since time immemorial, have bred and used the cow in their homes, community and society. While these ancient Indians were familiar with a large number of other animals, the cow has always been held and worshiped in maternal terms.
The sanctity of the cow is respected to this day. She is tame, gentle and the giver of milk. These were reasons enough to hold the cow in a very important and more special place than the rest of the animals but some people have associated some seemingly unscientific things with the cow. Cow is considered holy by the Hindus and to justify this worship of an animal certain people believed that the cow exhales Oxygen which is the mode of survival for human beings which makes the cow so special.
Cows, along with all vertebrates, use aerobic respiration, which means they take in Oxygen and give out Carbon Dioxide. It is a myth and a false belief that cows exhale Oxygen.
There is another superstition that exists, which claims the purity of cow urine; they say it has healing properties. Which is another wrong belief as it is the waste material of the body that is flushed out.
A cow is useful to mankind because it gives milk which feeds millions and cow dung is used as manure in plants and crops other than that the cow is a beautiful animal with no such traits as exhaling oxygen.