daf yomi arcade · chullin 80 · 2026-07-18
שֶׂה וַאֲפִילּוּ מִקְצָת שֶׂה
A koy is what happens when a wild deer and a domestic goat produce young. Half its blood is undomesticated, half is not — and the Rabbis rule that "sheep" in the Torah means שֶׂה וַאֲפִילּוּ מִקְצָת שֶׂה, even a partial sheep, while Rabbi Eliezer disagrees (80a:1). Rav Pappa then shows the koy's laws only make sense once you ask which parent was which. Two pens, two crosses, one riddle of paternity — sort the rulings, then meet the sages who never even agreed on what a koy is.
the pen — read before you sort
🐐🦌 Pen A — domestic sire, wild dam
תַּיִשׁ הַבָּא עַל הַצְּבִיָּיה — a buck goat mates a doe. The father is domestic, the mother is wild (80a:5).
🦌🐐 Pen B — wild sire, domestic dam
צְבִי הַבָּא עַל הַתְּיָישָׁה — a stag deer mates a nanny goat. The father is wild, the mother is domestic (80a:2, 5).
🧬 Why the pens differ
Both crosses raise the same doubt — חוֹשְׁשִׁין לְזֶרַע הָאָב, do we worry about the father's line? But which parent supplies the domestic half changes which law even applies, and how far "even a partial sheep" reaches. Rav Pappa maps six real rulings onto these two pens (80a:2–10) — your job is to put each ruling where it belongs.
learn the real daf
Chullin 80 opens with the koy — deer crossed with goat — and Rav Pappa's careful mapping of its laws onto two possible pedigrees. It moves through a real tannaitic dispute over what a koy even is, then into forest goats and Rabbi Yitzchak's count of exactly ten kosher species in Deuteronomy 14:4–5. The daf closes by turning to the mishna itself, where Rabbi Oshaya argues (80a:21) that its rulings on slaughtering an animal and its offspring don't follow Rabbi Shimon's view that an unfit act of slaughter isn't slaughter at all.