Hindus don't eat beef because in their religion, cows are seen as the symbol of life. Cows are protected animals in India, and most rural families own a cow that they treat as a member of the family.
Respect for cows in Hindu culture is derivative of the religion's major texts, some of which date back to Lord Krishna. He was a cowherd that appeared 5,000 years ago and was described as "the child who protects the cows." In modern India, milk from cows is central to cultural practices. Cows roam free in Hindu cultures, and it is seen as a sign of good luck to give one a snack.