By not taking the calves away from their mothers? That's how we did it for centuries, we only started taking calves away from their mothers when artificial milk replacements made it more profitable to do so.

I found a method that leaves them together for 3 months. That's an improvement at least.

(Of course that means that the calf will take most -but not all- of the milk during that time. But then it is stated that the cost for the vet goes down a lot in exchange.)

Another option I found is to give several calves to one cow for 6 months, which has advantages and disadvantages compared to the first way. (Longer time with milk and natural suckling behaviour but calves without their mother and the smaller ones might get less milk.)

edit: Here is a list with places in Germany that do that:

https://welttierschutz.org/hofliste-mit-mutter-oder-ammengeb...

I'm not sure how to translate the key words for english googling.