What, is it not referring to a bird, as he requires its blood to remove a moth from his garments? If so, apparently birds require slaughter by Torah law, as, if that were not the case, then even if a bird were stabbed, covering of the blood would be required. The Gemara rejects that proof: No, the baraita is referring to an undomesticated animal, as he requires its blood to use as a red dye [lelakka] Therefore, no proof may be cited from this baraita that birds require slaughter by Torah law.

The Gemara cites proof from a mishna (Zevaḥim 68a): Come and hear: If one cut the nape of the neck of a sacrificial bird with a knife instead of pinching it with his fingernail, this bird carcass renders the garments of one who eats the bird ritually impure when the meat is in his throat. The Gemara explains the proof: And if you say that slaughter of a bird is not obligatory by Torah law, then although when cutting the bird from the nape, he breaks the spine and the neck bone with the knife before severing the gullet and windpipe, and it indeed becomes a tereifa and may not be eaten, cutting the simanim with the knife should be effective to purify it, i.e., to prevent it from assuming the status of an unslaughtered carcass. The fact that the garments of one who swallows the meat of the bird become ritually impure indicates that slaughter is the only method effective in permitting the consumption of a bird and for preventing it from assuming the status of an unslaughtered carcass.

The Gemara rejects that proof: Although it is clear from that mishna that slaughter of birds is obligatory by Torah law, Rabbi Yitzḥak ben Pineḥas states his opinion in accordance with the opinion of that tanna who holds that it is not obligatory by Torah law, as it is taught in a baraita that Rabbi Elazar HaKappar, the distinguished Sage, says: What is the meaning when the verse states: “However, as the gazelle and as the deer is eaten, so shall you eat of it” (Deuteronomy 12:22)? And what now have we derived from the gazelle and the deer with regard to disqualified consecrated animals?

These two undomesticated animals come in the verse to teach a halakha with regard to disqualified consecrated animals, and it is found that a halakha is derived from the case of disqualified consecrated animals in their regard. The Torah juxtaposes a gazelle and a deer to disqualified consecrated animals to teach: Just as disqualified consecrated animals are rendered fit for consumption through slaughter, so too, a gazelle and a deer are rendered fit for consumption only through slaughter. But for a bird, slaughter is not obligatory by Torah law; rather, the obligation is by rabbinic law.

The Gemara asks: Who is the tanna who disagrees with Rabbi Elazar HaKappar and holds that the slaughter of a bird is obligatory by Torah law? It is Rabbi Yehuda HaNasi, as it is taught in a baraita: Rabbi Yehuda HaNasi says: The Torah states: “And you shall slaughter of your herd and of your flock, which the Lord has given you, as I have commanded you” (Deuteronomy 12:21). This verse teaches that Moses was previously commanded about the halakhot of slaughter, even though they are not written explicitly in the Torah. He was commanded about cutting the gullet and about cutting the windpipe, and about the requirement to cut the majority of one siman for a bird, and the majority of two simanim for an animal.

§ The mishna teaches that in the case of one who cuts one siman in a bird, his slaughter is valid. It was stated that there is an amoraic dispute with regard to this matter. Rav Naḥman said: One may cut either the gullet or the windpipe. Rav Adda bar Ahava said: One must cut the gullet for the slaughter to be valid, but cutting the windpipe is not sufficient. The Gemara explains the formulation of the mishna according to the opinion of each amora. Rav Naḥman said: One may cut either the gullet or the windpipe. One siman is taught in the mishna, meaning that the slaughter is valid if he severs one, indicating that either siman is valid. Rav Adda bar Ahava said: One must cut the gullet for the slaughter to be valid, but cutting the windpipe is not sufficient. What is the meaning of: One, in the mishna? It means the special one, the gullet.

The Gemara provides a mnemonic for the proofs to be cited by the Gemara: Slaughter, halves, windpipe, deficiency, of a bird sin offering.

The Gemara raises an objection to the opinion of Rav Naḥman from a baraita: If one cut the bird’s gullet and thereafter the windpipe was displaced, the slaughter is valid. If the windpipe was displaced and thereafter he cut the gullet, the slaughter is not valid. With regard to a case where one cut the gullet and the windpipe was found displaced and he does not know if it was displaced prior to the slaughter or if it was displaced after the slaughter, that was an incident that transpired, and the Sages said: In any case of uncertainty with regard to slaughter, the slaughter is not valid. The baraita mentions only the case of cutting the gullet, while cutting the windpipe is not taught. The baraita supports the opinion of Rav Adda bar Ahava and is contrary to the opinion of Rav Naḥman.

The Gemara rejects that proof: The baraita mentions only the cutting of the gullet and displacement of the windpipe not because slaughter may be performed only by cutting the gullet. Rather, those scenarios were mentioned because the windpipe, unlike the gullet, is likely to be displaced.

The Gemara suggests: Come and hear a proof contrary to the opinion of Rav Naḥman from a baraita. If one cut two halves, one half of each of the simanim, in a bird, the slaughter is not valid, as the requirement is that a majority of one siman is cut; and needless to say the slaughter performed in that manner is not valid in the case of an animal, where the requirement is that a majority of both simanim are cut. Rabbi Yehuda says: In a bird the slaughter is not valid until he cuts the gullet and the veins; the veins must be cut so that the blood will drain from the body. The fact that Rabbi Yehuda mentions cutting only the gullet and not the windpipe indicates that slaughter is valid only when the gullet is cut. The Gemara rejects that proof: Rabbi Yehuda mentions only the gullet because the gullet is adjacent to the veins.

The Gemara suggests: Come and hear proof in support of the opinion of Rav Naḥman from a baraita. If one cut half the windpipe and interrupted the slaughter for an interval equivalent to the duration of the slaughter of another animal, and then completed his slaughter, the slaughter is valid and it is not invalidated due to an interrupted slaughter. What, is the baraita not referring to the slaughter of a bird? And what does the term: Completed it, mean in the baraita? Doesn’t it mean that he completed cutting the windpipe, which he had started cutting, indicating that with the cutting of the windpipe the slaughter is valid, in accordance with the opinion of Rav Naḥman as opposed to the opinion of Rav Adda bar Ahava? The Gemara rejects that proof: No, the baraita is referring to slaughter of an animal, for which both simanim must be cut. And what does the term: Completed it, mean in the baraita? It means that he completed the entire slaughter.

The Gemara suggests: Come and hear proof in support of the opinion of Rav Naḥman from a baraita: In a case where half of the windpipe was deficient, i.e., somewhat cut, prior to the slaughter and the slaughterer added to that deficiency an incision of any size, and completed it, his slaughter is valid. What, is it not referring to the slaughter of a bird? And what does the term: Completed it, mean in the baraita? Doesn’t it mean that he completed cutting the majority of the windpipe, indicating that cutting the windpipe renders the bird fit for consumption? The Gemara rejects that proof: No, the baraita is referring to slaughter of an animal, for which both simanim must be cut. And what does the term: Completed it, mean in the baraita? It means that he completed the entire slaughter by cutting the gullet.

The Gemara suggests: Come and hear proof in support of the opinion of Rav Naḥman from a baraita: How does one pinch the nape of the neck of a bird sin offering? Using his thumbnail, the priest cuts the spine and the neck bone, without cutting through the majority of the surrounding flesh until he reaches either the gullet or the windpipe. Once he reaches the gullet or the windpipe, he cuts one siman with his nail and a majority of the surrounding flesh with it. And in the case of a bird burnt offering, he cuts the two simanim or the majority of the two simanim. The Gemara concludes: The refutation of the opinion of Rav Adda bar Ahava from this baraita is indeed a conclusive refutation.

The Gemara asks: What halakhic conclusion was reached about the matter? The Gemara asks in response: What halakhic conclusion was reached about the matter? It is as you said, that the opinion of Rav Adda bar Ahava was conclusively refuted. The Gemara says that there is not absolute proof from the baraita, as perhaps it is different there with regard to pinching, as in that case there is the spine and the neck bone that are cut initially, and therefore cutting the windpipe is sufficient. But in the case of slaughter of a non-sacred bird, perhaps only if one cuts the gullet the slaughter is valid.

The Gemara asks: What then is the halakha in the case of slaughter? The Gemara answers: Come and hear proof from the following incident, that there was a certain duck that was in the house of Rava, which came for slaughter with its neck filthy with blood and they did not know whether the blood was the result of its windpipe having been severed or its gullet having been perforated, in which cases the duck is a tereifa. Rava said: What should we do with regard to this duck?