The Studding Protocol is not able to allow for Base Animals that will result in burn to be breed. This limitation is for 2 reasons:
CryptoZoo has provided no on-chain way to calculate an Animals Accrued Yield. This makes it impossible for the Studding Protocol to know how much $ZOO to return to the Studder if breeding results in the Base Animal burning.
The Accrued Yield upon Animal burn is not transferred in the same transaction. It appears that the Accrued Yield is transferred in a separate transaction via a centralized server hosted by CryptoZoo. This prevents smart contracts like the Studding Protocol from creating atomic transaction involving Accrued Yield.