Mama milk cow

Allow me, if you will, to display my ignorance for a moment. One of my coworkers owns a dairy farm in a nearby town, and she was telling me this morning how they use computer technology to track how much milk the cows are producing and when they need to have another calf to up their milk production. On a basic level, this is common sense. This is how the world works. When a mother mammal has a baby, she produces milk for the little one. But for some reason it had never occurred to me that dairy cows had to continually have babies in order to keep producing milk. It makes perfect sense, but I had never considered it before. I guess I just assumed that dairy cows were a specific type of cow that just produced milk. So there you go. Make fun of me if you wish.