• Shechitah on Shabbos is valid, but this Mishnah prohibits eating it on Shabbos

The next Mishnah states: השוחט בשבת וביום הכיפורים – if one shechts an animal on Shabbos or Yom Kippur, אף על פי שמתחייב בנפשו – even though he becomes liable with his life (i.e., incurs the death penalty on Shabbos or כרת on Yom Kippur), שחיטתו כשרה – his shechitah is still valid, and the meat may be eaten. Rav Huna quoted in Rav’s name that although the shechitah is valid, אסורה באכילה ליומא – it is forbidden in consumption for that day, i.e., it is prohibited until after Shabbos (this is inferred from the Mishnah’s mentioning shechting on Shabbos “or Yom Kippur,” suggesting a comparison between Shabbos and Yom Kippur, when the meat certainly cannot be eaten). ונסבין חבריא למימר רבי יהודה היא – And the colleagues in the yeshiva thought to say (in explanation of Rav’s statement) that [the Mishnah] is Rebbe Yehudah, who would forbid eating the meat on Shabbos itself. The Gemara embarks on a lengthy search to identify the relevant ruling of Rebbe Yehudah, and why the meat is forbidden on Shabbos.

• רבי יהודה דהכנה: prohibiting cutting up a נבילה for dogs

Rebbe Abba suggests that it refers to Rebbe Yehudah’s ruling about "הכנה" – preparation (i.e., items lacking “preparation” for Shabbos). A Mishnah teaches that one may cut up a נבילה on Shabbos for dogs to eat, but Rebbe Yehudah says that if it was not already a נבילה before Shabbos, it is prohibited, לפי שאינה מן המוכן – because it was not something prepared for Shabbos use, and is מוקצה. Here, too, an animal which was shechted on Shabbos was not prepared the day before for Shabbos use, and is מוקצה.

Abaye rejects the comparison, because in the case of the neveilah, מעיקרא מוכן לאדם- it was initially prepared for human consumption when it was alive when Shabbos began, והשתא מוכן לכלבים – and now that it died it is prepared for consumption by dogs (it is therefore מוקצה, since it was not previously prepared for such Shabbos use). In contrast, a shechted animal was always prepared for human consumption, and should not be מוקצה!? Although Rebbe Abba argues that a live animal was previously designated לגדל – for breeding (and not consumption), Abaye disproves this, because if so, Rebbe Yehudah would not permit shechting animals on Yom Tov.

• Comparing newly broken כלים and a shechted animal (אוכלא דאיפרת)

Rav Yosef suggests that it refers to Rebbe Yehudah’s ruling about כלים. A Mishnah teaches that any כלים which are not מוקצה which broke on Shabbos, שבריהן ניטלין – their fragments may also be moved, provided they are fit to perform מעין מלאכה – some sort of task, even if it is different from the original כלי’s function (e.g., using pieces of a mixing bowl to cover a barrel). However, Rebbe Yehudah says the fragments may only be moved if they can perform functions מעין מלאכתן – similar to their original task (e.g., using pieces of a mixing bowl for containing porridge poured into them). Since a shechted animal was not formerly usable as food, it is likewise מוקצה. Abaye rejects the comparison: regarding broken utensils, מעיקרא כלי – it was initially a utensil, והשתא שבר כלי – and now on Shabbos it became a fragment of a utensil. This is נולד – something newly created, and מוקצה. In contrast, an animal was food when it was alive, and food after being shechted; אוכלא דאיפרת הוא – [a shechted animal] is merely food which was broken apart, and not a newly created item. This can be demonstrated from Rebbe Yehudah’s permitting some cases of juice which flowed out of fruit, and he does not consider it נולד.

This discussion continues on the next Daf.