They only need to be pregnant once. The calf milk is different than normal milk and can not be sold. The stuff we drink is what happens after a calf is born but you never stop milking so the cow stays productive. I think you need to revisit mamal biology. Once the process of Milk production is started milk will be produced in most mammals till the long term cessation of mamary tisssue stimulation.
They only need to be pregnant once. The calf milk is different than normal milk and can not be sold. The stuff we drink is what happens after a calf is born but you never stop milking so the cow stays productive. I think you need to revisit mamal biology. Once the process of Milk production is started milk will be produced in most mammals till the long term cessation of mamary tisssue stimulation.