Why would the calves be kept near the cows? They’re not gonna feed the milk that their mothers are producing for them, because that would mean less milk to sel

Why would the calves be kept near the cows? They’re not gonna feed the milk that their mothers are producing for them, because that would mean less milk to sell and less milk for people to consume. And so why keep the calves in the milking side of the facility when you can move them to the fattening side for meat/leather or to get them to age so you can forcibly impregnate them every year for their milk, depending on their gender.