I believe everyone knows that cow in Hinduism is a sacred animal. For ages cow has been important in the lives of the Indians. They use milk as food, cow-dung as fuel and, if mixed with clay, for plastering huts. Cows play a role of a dowry for daughters and a bribe for Brahmans for a place in paradise. Another reason why the cow is considered sacred is based on the belief that Hindus can reach heaven only after crossing a mythological river, and to cross this river is possible only by holding the tail of the cow.
Killing a cow is the greatest sin. Allowing someone to kill a cow or eating beef is also a sin. Even if a cow dies a natural death at home - it is also a sin for the owner of the house. If you do one of that you will be in hell for as long as many hairs are on the cow’s skin. Or seven times you will be born a seriously ill, a eunuch or a martyr. Anyway, there is a way to avoid this sad fate. To clean yourself from the sin of killing a cow you should undertake a pilgrimage to all the holy cities of India holding a stick with the cow’s tail. Or you should put on the skin of the killed animal, wear a rope around your neck and go around with a wisp of straw in your mouth. It is unclear for how long you have to go around like that...probably as long as Brahman will say. 

