Milk was obtained from several different animals during period. Commonly milked were cows, sheep, goats and, in some parts, mares and even yak.
Cow's milk contains levels of lactose, to which some people are allergic or intolerant. It is wise to let your guests know if you have used milk in any dishes at a feast.
Milk, when fresh from the beast, can be used to make cream, butter, yoghurt, ghee and cheese.
Mare's milk can also be used to make koumiss.