This demonic world is the greatest enemy of cows. Just see how they are maintaining hundreds and thousands of slaughterhouse. Hundreds and thousands of slaughterhouse. Innocent animals, giving you milk, the most important foodstuff. Even after death, it is giving you its skin for your shoes, and you are so rascal that you are killing. And you want to be happy in this world. You see? How sinful they are! They have no consideration that this animal…

Why cow protection is so much advocated? Because it is very, very important.

From Srila Prabhupada's lecture on Srimad-Bhagavatam 1.8.43 — May 5, 1973, Los Angeles