B'choros, 37a: It includes a B'chor whose cartilage of the ear is nicked in the Din of Ba'al-Mum. ¹

Sifri #1: It includes animals with various kinds of boils, ² or which are old, sick and sweaty (whose breath reeks) in the realm of Ba'alei-Mumin. ³

Sifri #2: It includes animals that are born with blemishes. ⁴

R. Bachye: It teaches us that the Kohen ¹ may eat Pesulei ha'Mukdashin outside the Beis-Hamikdash. ²

R. Bachye: We learn that the Kohen ¹ is permitted to eat Pesulei ha?Mukdashin whether he is Tamei or Tahor ² ? as opposed to Basar Kodesh, for which he would be Chayav Kareis.

Yevamos, 73b: We learn that a Tahor person is permitted to eat Pesulei ha'Mukdashin together with a Tamei person from the same dish - and we are not concerned that the Tahor person might touch the Tamei one ³ or that he is eating Pesulei ha'Mukdashin that are Tamei. ⁴

Bechoros, 32b & 33a: See answer #1. And how much more so is a Kohen (the owner of the B'chor under discussion) permitted to invite a Zar and or a Nidah to eat from it. ⁵ .

Yerushalmi Bikurim, 2:1: It precludes Terumah, which a Tahor Kohen is not permitted to eat together with one who is Tamei, since the latter renders the Terumah Tamei - and a Tahor Kohen is not allowed to eat Tamei Terumah. ¹

Bechoros, 33a): In order to permit feeding Pesulei ha'Mukdashin even to a Nochri - just as the Nochri is permitted to eat the meat of a deer and a gazelle (Chayos, which can never attain Kedushas ha'Guf). ¹

Refer to 12:15:5:1-3.