Bikkurim 2:10-11

Bikkurim 2:10

A koy is like a domesticated animal in that its cheilev fats are prohibited like those of domesticated animals, though one would not be liable to kareis (spiritual excision) if he ate them (because a koy might be a wild animal). A koy’s cheilev may not be purchased with second-tithe money to consume in Jerusalem and the shoulder, cheeks and abomasum must be given to a kohein, as with domesticated animals. Rabbi Eliezer says that one who slaughters a koy need not give these portions to a kohein because the burden of proof is on the kohein to prove that the koy is in fact a domesticated animal.

Bikkurim 2:11

A koy is like neither a wild nor a domesticated animal in that one may not crossbreed it with either kind. If a person gifts his wild and domesticated animals to his son, the koy is not included. If a person declares himself a nazir if the koy is a wild animal, or if it is a domesticated animal, he is a nazir (because we act stringently in a case of doubt). In all other ways, the koy is treated like both a wild and a domesticated animal: it requires ritual slaughter like both, and its carcass and severed limbs convey ritual impurity like both. (That last part might be understood as “its carcass conveys ritual impurity and its severed limbs may not be eaten like both.”)