Shouldn't it be possible to give the calf all the milk until it's old enough to wean, but keep milking the mother.
I think that's what they used to do in the days of sustenance farming.
Of course, if the calf was a boy they would slaughter it about then. But that's another discussion entirely.
The farmer in the article does it that way. Cows produce the most milk right after birth. Then they reduce the production, because the calve starts eating on its own.
I think keeping the calves with the mothers is the smallest part of the problem. The premature slaughter of cows and the slaughter of male calves and "surplus" female calves is the bigger issue for me.
Apparently the cows now produce way more milk per day than the calf needs. The wikipedia also says calves grow a lot faster when kept with their mother.
Of course, if the calf was a boy they would slaughter it about then. But that's another discussion entirely.