Go-raksya means protection to the cows. Instead of protection to the cows, they are killing the cows. How you can have perfect society? Cows must be protected. It is so important animal. It is giving the you nectarean food milk, and from milk, you can save your children, you can save your diseased persons. And how it is that you take the cow's milk and send it for slaughterhouse. Oh, this is not, not at all human civilization. Here it is said go-raksya. You should give all protection to this important animal. Krsna does not say that you should protect the pigs and hogs or other animals. He especially meant the cows because cow is very important animal to the human society. If there are meat-eaters, they can kill other animals, but they should not kill the cow. This is, if you want actually perfect society. Krsi-go-raksya-vanijyam [Bg. 18.44].
From Srila Prabhupada's lecture on Bhagavad-gita 18.41 – Stockholm, September 7, 1973