• שחיטה לעוף מן התורה

On the previous Daf, Rebbe Yitzchak ben Pinchas said: אין שחיטה לעוף מן התורה – there is no law from the Torah requiring shechitah of birds by cutting the סימנים; rather, tearing or stabbing them suffices (however, shechitah is required מדרבנן). He darshens "ושפך" – he shall pour out (the blood) to teach: בשפיכה בעלמא סגי – merely pouring out its blood is sufficient for slaughtering it. The Gemara eventually concedes that this question is a machlokes Tannaim. Rebbe Elazar Hakkapar the Great darshens the Torah’s comparison between פסולי המוקדשים – disqualified korbanos which were redeemed and איל וצבי – a deer and a hart to teach that non-domesticated animals require shechitah just as disqualified korbanos do, ועוף אין לו שחיטה מדברי תורה – but a bird has no shechitah requirement according to Torah law, אלא מדברי סופרים – only by Rabbinical decree. Rebbe darshens: "וזבחת...כאשר צויתיך" – and you shall slaughter…as I have commanded you, מלמד שנצטוה משה על הושט ועל הקנה – this teaches that Moshe was orally commanded regarding [shechting] the trachea and esophagus, ועל רוב אחד בעוף – and about cutting most of one pipe of a bird, ועל רוב שנים בבהמה – and about cutting most of two pipes of an animal.

• Can the “one סימן” requirement of birds be either סימן, or specifically the וושט?

The Mishnah taught that shechitah of one סימן is sufficient for a bird. Rav Nachman says: או וושט או קנה – either the esophagus or the trachea qualifies. Rav Ada bar Ahava says: וושט ולא קנה - he must specifically shecht the esophagus, and not the trachea, and the Mishnah’s term "אחד" means "מיוחד" – the special pipe. The וושט is the more critical סימן, since even a tiny hole in the וושט renders the animal a טריפה, whereas only a mostly cut קנה does. A Baraisa states that melikah of a חטאת העוף can be performed on either סימן, apparently disproving Rav Ada bar Ahava. However, the Gemara suggests that melikah is different, since the spinal cord and neck bone are also cut during melikah. Therefore, the Gemara presents an incident about a duck in Rava’s house whose neck was stained with blood. Rava wondered how to examine the וושט for fatal injuries, since the וושט must be examined from the inside, and if they shecht it first, they may shecht through a fatal hole in the וושט. Rava’s son suggested examining the קנה externally and shechting it, and examining the וושט internally afterwards, and Rava approved. This proves that one may shecht either סימן of a bird.

• Is מחצה על מחצה כרוב?

Rav says: מחצה על מחצה כרוב – shechting a סימן until it is half-cut and half-uncut is like having shechted most of the סימן, and is a valid shechitah. He explains: הכי אמר ליה רחמנא למשה – Hashem said thus to Moshe: "לא תשייר רובא" – “Do not leave most of the סימן uncut” (but cutting half is sufficient). Rav Kahana says מחצה על מחצה is not כרוב, and explains: הכי אמר ליה רחמנא למשה – Hashem said thus to Moshe: "שחוט רובא" – “Shecht most of the סימן” (not merely half). Although the Mishnah clearly states that shechting half a סימן is invalid, Rav can explain that our Mishnah’s ruling is מדרבנן, דלמא לא אתי למעבד פלגא – lest one may not come to [cut] even half the סימן. On the next Daf, Abaye concludes that all Amoraim agree that מחצה על מחצה אינו כרוב, and their machlokes concerns a completely different subject.