The following conversation with Srila Prabhupada very nicely elaborates on why cows are the most essential animal in society and why we should not kill them unnecessarily.
Prabhupāda: And dahī also.
Revatīnandana: Yes. Everything from the cow.
Revatīnandana: The cow, providing everything nice.
Prabhupāda: Cow is so important. These vegetable, grains and cow. Bās, finished. You can make hundreds and thousands of preparation. Why the poor animals should be killed? Take as much possible. And those who are flesh eaters, let the animal die—eat. Why lifetime should be killed? In India that is the process. Those who are flesh-eaters, when the cow dies, they are called, "You can take." Cobbler. So they get the skin, the hoof, the horn, they eat the flesh. So that's all right. Finished. And they keep the bones also for manure. Yes. After death. That is the system in India. Whenever a man's cow dies, this class of men, cobbler, they are called, "You take it." They will take it.
Pradyumna: I do not think many children like to eat meat.
Pradyumna: Many children do not like to eat meat. They are trained to eat meat.
Prabhupāda: This is unnatural.
Pradyumna: I did not . . . when I was . . . I did not like to eat it, but they trained.
Revatīnandana: Even from the economic side, they waste so much land for keeping a few animals for slaughter. They could grow large quantities of grains, fruits, everything. Instead, all the land now is devoted to slaughter, and they have to import grains, fruits, other things in England. The whole countryside is beautiful country, all like this. The whole country. And everywhere is nothing but slaughter business. And they could grow everything, everything that they need. In fact, that can be . . . we can . . . eventually we can, we can do that. And this country would become self-sufficient. Now it has to import so many things.
Prabhupāda: Yes. Vacant land.
Revatīnandana: It takes many acres of land to keep one animal. On the same acreage you can produce enough food for several men for a whole year.
Prabhupāda: Both for the animal, both for the man. Just educate them, these rascals.