Srila Prabhupäda: So if the cow is your mother, how can you support killing her? You take the milk from her, and when she’s old and cannot give you milk, you cut her throat. Is that a very humane proposal? In India those who are meat-eaters are advised to kill some lower animals like goats, pigs, or even buffalo. But cow killing is the greatest sin. In preaching Krsna consciousness we ask people not to eat any kind of meat, and my disciples strictly follow this principle. But if, under certain circumstances, others are obliged to eat meat, then they should eat the flesh of some lower animal. Don’t kill cows. It is the greatest sin. And as long as a man is sinful, he cannot understand God. The human being’s main business is to understand God and to love Him. But if you remain sinful, you will never be able to understand God—what to speak of loving Him.