SACRED COWS IN INDIA

Cows are the mothers of the universe
The human infant is fed breast milk by its human mother for under three years. After weaning, the cow acts as the surrogate mother providing milk for the rest of the human life-through childhood, adult age and old age. Cow is verily the mother of the world. One would be filled with repugnance at the ungrateful idea of killing mother, whether surrogate mother or otherwise.). 

Bhishma said:

No sacrifice can be performed without the aid of curds and ghee (clarified butter). The very character of sacrifice which sacrifices have, depends upon ghee. Hence ghee (or, the cow from which it is produced) is regarded as the very root of sacrifice.
Cows have been said to be the limbs of sacrifice. They represent sacrifice itself. Without them, there can be no sacrifice. With their milk and the Havi produced therefrom, they uphold all creatures by diverse acts. Cows are guileless in their behaviour. From them flow sacrifices and Havya and Kavya, and milk and curds and ghee. hence cows are sacred.
Afflicted by hunger and thirst, they bear diverse burdens.
Cows support the Munis (sages).
Among all objects mobile and immobile, the mobile are
superior. Among mobile creatures Brahmanas are superior.
The sacrifices are all established upon them. It is by sacrifice that Soma (nectar) is got. Sacrifice has been established upon cows. ( For without ghee or clarified butter, which is produced from milk, there can be no sacrifice). The gods become gratified through sacrifices. It is from the cows that the means have flowed of the sustenance of all the worlds. They yield Soma (nectar) in the form of milk. Cows are auspicious and sacred, and grantor of every wish and givers of life.
They who make gifts of cows, and who subsist upon the remnants of things offered as libations on the sacred fire, are regarded, as always performing sacrifices of every kind.
Of all kinds of gifts, the gift of cows is applauded as the highest. Cows are the foremost of all things. Themselves sacred, they are the best of cleansers and sanctifiers. People should cherish cows for obtaining prosperity and even peace. Cows are said to represent the highest energy both in this world and the world that is above. There is nothing that is more sacred or sanctifying than cows.
One should never feel any repugnance for the urine and the dung of the cow.

[Note: The following comments are by the scholar and translator of The Mahabharata Sri Kisari Mohan Ganguli: The Rishis (ascetic seers) discovered that the magnetism of the cow is something that is possessed of extraordinary virtues. Give the same kind of food to a cow and to a horse. The horse-dung emits an unhealthy stench, while the cow-dung is an efficacious disinfectant. There can be little doubt that the urine and dung of the cow possess untold virtues.]

Vyasa said:

Cows are sacred. They are embodiments of merit. They are
high and most efficacious cleansers of all.
One should for three days drink the hot urine of the cow. For the next three days one should drink the hot milk of the cow. Having thus drunk for three days hot milk, one should next drink hot ghee for three days. Having in this way drunk hot ghee for three days, one should subsist for the next three days on air only.

Vasishtha said:

By bathing in water mixed with cow-dung, people shall become sanctified. The deities and men, shall use cow-dung for the purpose of purifying all creatures mobile and immobile. One can sit on dried cow dung. One should never eat the flesh of cows.
One should never show any disregard for cows in any way. If evil dreams are seen, men should take the names of cows. One should never obstruct cows in any way. Cows are the mothers of both the Past and the Future. Cows have become the refuge of the world. It is for this that cows are said to be highly blessed, sacred, and the foremost of all things. It is for this that cows are said to stay at the very head of all creatures. Every morning, people should bow with reverence unto cows.
Cows are the best Havi for the deities. The Mantras called Swaha and Vashat are forever established in cows. Sacrifices are established in the cows. Cows constitute the fruit of sacrifices.Cows are the future and the past, and Sacrifices rest on them. Morning and evening cows yield unto the Rishis, Havi for use in Homa (sacred fire ceremony).
Cows are always fragrant. The perfume emanated by the exudation of the Amytis agallochum issues out of their bodies. Cows are the great refuge of all creatures. Cows constitute the great source of blessing unto all. (Swastayana is a ceremony of propitiation, productive of blessing and destructive of misery of every kind). Cows are the source of eternal growth.
Cows are sacred. They are the foremost of all things in the world. They are verily the refuge of the universe. They are the mothers of the very deities. They are verily incomparable.
Cows are the mothers of the universe.
There is no gift more sacred than the gift of cows. There is no gift that produces more blessed merit. 

Vyasa said: 

Cows constitute the stay of all creatures. Cows are the refuge of all creatures. Cows are the embodiment of merit. Cows are sacred and blessed and are sanctifiers of all.
One should never, in even one's heart, do an injury to cows. One should, indeed, always confer happiness on them.
Living in a pure state, in the midst of cows, one should mentally recite those sacred Mantras that are known by the name of Gomati, after touching pure water. By doing this, one becomes purified and cleansed. Brahmanas of righteous deeds, who have been cleansed by the knowledge, study of the Vedas, and observance of vows, should, only in the midst of sacred fires or cows or assemblies of Brahmanas, impart unto their disciples a knowledge of the Gomati Mantras which are every way like unto a sacrifice (for the merit they produce). One should observe a fast for three nights for receiving the boon constituted by a knowledge of the import of the Gomati Mantras.
The man who is desirous of obtaining a son may obtain one by adoring these Mantras. He who desires the possession of wealth may have his desire gratified by adoring these Mantras.
The girl desirous of having a good husband may have her wish fulfilled by the same means. In fact, one may acquire the fruition of every wish one may cherish, by adoring these sacred Mantras. When cows are gratified with the service one renders them, they are, without doubt, capable of granting the fruition of every wish. Even so, cows are highly blessed. They are the essential requisites of sacrifices. They are grantors of every wish. Know that there is nothing superior to cows.

 Cows are endued with the elements of strength and energetic exertion. Cows have in them the elements of wisdom. They are the source of that immortality which sacrifice achieves.
They are the refuge of all energy. They are the steps by which earthly prosperity is won. They constitute the eternal course of the universe. They lead to the extension of one's race.

Bhishma said:

One should not, by imparting a knowledge of this ritual, benefit a person that is not one's disciple or that is not observant of vows or that is bereft of faith or that is possessed of a crooked understanding. Verily, this religion is a mystery, unknown to most people. One that knows it should not speak of it at every place. There are, in the world, many men that are bereft of faith.
There are among men many persons that are mean and that resemble Rakshasas. This religion, if imparted unto them, would lead to evil. It would be productive of equal evil if imparted to such sinful men as have taken shelter in atheism.

From the Mahabharata, Anusasana Parva, Sections LXXXIII, LXXVII & LXXVI available in http://www.hinduism.co.za/cowsare.htm. Adapted and illustrated to be posted by Leopoldo Costa