Reference for Bekhorot 13:35
דאיעבר מקלוט בן פרה ואליבא דרבי שמעון קאמר
For R'Joshua B'Levi said: There can be no impregnation either of an unclean animal from a clean animal, or of a clean animal from an unclean animal, or of large cattle from small cattle, or of small cattle from large cattle, or of a domestic animal from a beast of chase, or a beast of chase from a domestic animal, except in the case<span class="x" onmousemove="('comment',' A koy: (An antelope or bearded deer) . The Rabbis are undecided whether it belongs to the genus of cattle or the beasts of the chase. This animal, however, comes from a he-goat, and a hind, and R. Eliezer and the majority of the Sages dispute whether the law forbidding the killing of the mother and its young on one day applies to it. But apparently they agree that impregnation is possible in such circumstances.');"><sup>15</sup></span>