Leviticus 27:26-27

26“ ‘No one, however, may dedicate the firstborn of an animal, since the firstborn already belongs to the LORD ; whether an ox The Hebrew word can refer to either male or female. or a sheep, it is the LORD ’s.

27If it is one of the unclean animals, it may be bought back at its set value, adding a fifth of the value to it. If it is not redeemed, it is to be sold at its set value.