I understand that the cow is sacred but I don't know if this extends to all animals. I am not clear as to whether avoidance of meat is only out of respect for the animal or if abstinence also helps the individual become more spiritual in some way?
Yes, Krishna Agarwal is right but yet there are one or two points to clarify.
In India, people believe in non-violence because according to Indian religious belief, there are soul in every body and soul is the part of God. Secondly, man is not born to take meat and that is why we don't have the same teeth as other creatures have who live on meat. To take meat we need to cook it.
Then there is Vaishnabites who believe in vegetarian. We are not suppose to kill another animal for our enjoyment God has created all and we are man because we have intellect, speech and so on and so we are called the best creature in the world. We should try to have control over our mind not to be violent. Taking meat give more energy and it inspires people to act violently.
Besides, people in India worship different gods, even sacrifice animals, birds to deities for peace and to fulfill their earthly desires. The main scripture of the Hindus Srimadbhagawat says the more you aspire, the more you commit sin and going to be born in those animal bodies or trees, creepers after death. Most Hindus are very cautious to follow the techings of the scripture stictly. Hence they feel commiting sin killing other creatures or eating their flesh.
However, the new generations have adopted liberally and discarded the teaching which kept us together calm and peaceful.
No, vegetarianism is not a mandatory part of either Hindu or Buddhist faith. However a large number of Hindu's are vegetarian by tradition and culture. I am not sure if there are many Buddhist who practice vegetarianism. Most of the Buddhist today belong to countries where, vegetarianism is not a part of their popular culture. Though the Buddhist faith originated in Indian subcontinent, it lost its identity in India as a religion or sect different from Hinduism long back. There are not many Buddhist in India. Most of the Buddhist that do exist in India are called Neo-Buddhists, who have adopted this religion, in twentieth century, more as a political rather than religious action.
Referring specifcally to cow, yes, it is sacred among Hindu's, and most of the Hindus, who do not mind eating other non-vegetaran food, do not eat beef (flesh of cow).