[If] it developed a blemish during its [first] year, it is permissible to keep it for the entire twelve months; after its [first] year, he may keep it only until thirty days.

[If] one slaughters a bechor and [then] shows its blemish —- R’ Yehudah permits [it]; R’ Meir [however] says: Since it was slaughtered without the sanction of an expert, it is forbidden.