These good girls that can produce up to 10 gallons a day if they are well groomed and very happy.
In order for that to happen, they have to have sex daily, and all the food they want (they are grass fed, sometimes some proteins), plus they need to sleep 8 hours a day and workout a minimum of 30 minutes a day. They do not need to be bred because they are genetically produced, although they can get pregnant, but when they have children they actually produce less milk since it's only for children.