| Almost this. The better answer is because we want to get ALL the milk. So instead of letting the mother cow nurse her calf for the first few months and then start taking her milk for our use, the more "modern" practice is to separate the calf immediately. Which means if you are drinking milk, you are drinking it from seriously depressed cows. I wonder how this contributes to our culture's growing mood of depression? see i.e. https://www.theguardian.com/environment/2019/jun/29/mums-ask... or just google dairy cows separate from calves |