Buddha ate beef. So did ancient Hindus.
Depends on what scripture you follow:
According to the story of the Nirvana Sutra, a Mahayana Buddhist scripture purporting to give the Buddha's final teachings, the Buddha insisted that his followers should not eat any kind of meat or fish, even those not included in the 10 types, and that even vegetarian food that has been touched by meat should be washed before being eaten. Also, it is not permissible for the monk or nun just to pick out the non-meat portions of a diet and leave the rest: the whole meal must be rejected.[7]
Chapter 7 of the Nirvana Sutra (translated by Kosho Yamamoto and edited by Dr. Tony Page) states:
One who eats meat kills the seed of great compassion... O Kasyapa! I, from now on, tell my disciples to refrain from eating any kind of meat. O Kasyapa! When one eats meat, this gives out the smell of meat while one is walking, standing, sitting or reclining. People smell this and become fearful. This is as when one comes near a lion. One sees and smells the lion, and fear arises. O good man! When one eats garlic, the dirty smell is unbearable. Other people notice it. They smell the bad smell. They leave that person and go away. Even from far off, people hate to see such a person. They will not come near him. It is the same with one who eats meat. It is a similar situation with all people who, on smelling the meat, become afraid and entertain the thought of death. All living things in the water, on land and in the sky desert such a person and run away. They say that this person is their enemy. Hence the Bodhisattva does not eat meat.
Buddhist vegetarianism - Wikipedia, the free encyclopedia