Rules for Firstborn Animals

Leviticus 27:26-27

The firstborn, which belong to the Lord, no man may sanctify and vow: whether it be bullock, or sheep, they are the Lord's.

And if it be an unclean beast, he that offereth it shall redeem it, according to thy estimation, and shall add the fifth part of the price. If he will not redeem it, it shall be sold to another for how much soever it was estimated by thee.