1,170. Non-Jews, Kohanim, Leviim

177:12 If a Jew buys an animal from a non-Jew and it's not known whether or not this animal has previously given birth, and it subsequently gives birth in the Jew's possession, the offspring is a doubtful first-born. Even if the non-Jew says - without understanding the ramifications of his statement - that the animal had already given birth, it is of no consequence. Also, signs in the animal's horns are of no consequence. Even if the is producing milk it doesn't matter unless we see it feeding her young. If the animal is producing milk and the non-Jew additionally mentions - without understanding the halachic ramifications - that the animal has already given birth, this is sufficient to establish it for cows but not for goats.

177:13 Kohanim and Leviim are also obligated in the mitzvah of first-born kosher animals. The only difference is that a kohein puts the animal aside and keeps it for himself. He must treat it as a sanctified first-born animal.