I used to get my milk from a local organic farm. The farmers kept the baby calf with its mother. I visited the farm once a month and I saw for myself how the calves were treated.
It was a farm, so the animals were not pets. However, the calves were not separated from their mothers. The male calves were slaughtered when weaned and the meat was old as rose beef. It was delicious.
I bought milk from this farm because I was OK with the way the animals were treated. The male calves might have had shorter lives, but they were pastured, spent their time with their mothers and other calves out in the fresh air and sunshine, and were humanely treated.
When this farm was sold, I could no longer find a source of milk I felt was reasonably humane so at this point in time I do not buy milk.
I don't have an issue with the circle of life - in the wild, carnivores kill to eat. What I have a problem with is torture.
Animals have basic needs that should be met. Sunshine and fresh air rank up there. So does being with their mother.
The cruelty of separating a baby from its mother is so horrible... yet we do this to dairy calves, and also to animals used in experimentation, and even to pets - too often people will adopt a puppy too early, taking it away from its mother way too young. People need to realize that animals are not just there for their convenience, their needs should also matter.