Slaughter is the way of sub-humans…. The animal killers do not know that in the future the animal will have a body suitable to kill them. That is the law of nature. In human society, if one kills a man he has to be hanged. That is the law of the state. Because of ignorance, people do not perceive that there is a complete state controlled by the Supreme Lord. Every living creature is a son of the Supreme Lord, and He does not tolerate even an ant’s being killed. One has to pay for it. So indulgence in animal killing for the taste of the tongue is the grossest kind of ignorance. A human being has no need to kill animals, because God has supplied so many nice things. If one indulges in meat-eating anyway, it is to be understood that he is acting in ignorance and is making his future very dark…. Human society is advancing in the wrong direction and is clearing the path to its own condemnation.

Srila Prabhupada, Bg 14.16, ppt.