Bekhorot 9: A Lamb for the First-Born Donkey

A new mishnah! When two donkeys are born at the same time, and it's not clear which one should be offered as a first-born (or a male and female and not clear which was born first). Also, the redemption of the first-born donkey with a lamb (or a kid). Note that a lamb can be used multiple times to redeem a donkey, given the proper procedure. Also, the Gemara delves into the case of designating a lamb as a possible redeemer -- with the sharp question why the owner who designates the lamb has to designate, since it will remain in his possession regardless.