Reference: I explained this in Kesuvos (6a) and in Shabbos (111a. Some say that it is forbidden lest he squeeze water from it. R. Tam challenged this, for squeezing of laundering applies only to water. Others forbid lest he be Mevatel (leave the cloth there permanently), and he made a Kli on Shabbos, or due to Mefarek.)

Implied suggestion: We can learn from here that one may detach feathers from a bird's neck in order to slaughter on Yom Tov!

Rejection: Above (24b DH v'Hainu, Explanation #2) I explained that it is permitted because he does not intend [to detach. Here he intends.]

Implied question: According to the version that I explained (there, i.e. Explanation #1) that it is permitted even if he intends (also here we should permit)!

Answer: That is only for wool, but for feathers it is not ki'Le'acher Yad, like it teaches below about one who plucks [a feather from] a bird's wing, that it is normal.

Implied question: He does not need the feathers. It is Melachah she'Einah Tzerichah l'Gufah! (We rule like R. Shimon, that it is forbidden only mid'Rabanan. It should be permitted for the sake of Shechitah, just like uprooting something from where it grows ki'Le'acher Yad!)

Answer: We cannot learn Melachah she'Einah Tzerichah l'Gufah from ki'Le'acher Yad.

Question: What was the question? Even though regarding Bechor he is not liable due to Lo Sagoz, regarding Shabbos we can obligate for a Toldah of Gozez, like anyone who uproots something from where it grows on an animal!

This is like one who stuck his hand into an animal's womb and uprooted the fetus in its womb. Regarding Shabbos he is liable, and one who did so to Kodshim is not liable for Gozez.

And similarly Kituf (harvesting by hand) is liable on Shabbos for a Toldah of Kotzer, and everyone who detaches from what is attached, even though one is not liable for Kituf for harvesting before the Omer (Pesachim 11a), and regarding Leket, in Chulin (137a).

Answer: If we would explain here that he challenges what we said that Tolesh is considered ki'Le'acher Yad, it would be fine that he brings a proof from here that it is not ki'Le'acher Yad.

Objection: The wording does not connote like this, since it says "is Tolesh not Gozez?! A Beraisa teaches that one who is Tolesh from a wing..." This connotes that he challenges what we said that Tolesh is not Gozez.

Explanation: [R. Yosi holds like Rav,] who forbids Davar she'Eino Miskaven;

If he permitted Davar she'Eino Miskaven, what is Rav's source that the Halachah follows him because Tolesh is not Gozez? Perhaps R. Yosi permits because Davar she'Eino Miskaven is permitted, but Tolesh is Gozez!

Rather, Rav knew that R. Yosi forbids Davar she'Ein Miskaven.

Explanation: This is written in most Seforim. We can explain that it mentioned that the end reddens for a bigger Chidush, that even though it is all red outside, it must be sheared [to be Machshir it for Parah Adumah].

Alternative text: Rashi's text says oppositely (it is red at the root and black at the end), based on the Tosefta in Parah (2:7).

Explanation #1: [He need not be concerned] even if he cuts other hairs with [the black hairs] without intent, or even these [black hairs] themselves he cuts more than is needed, according to Rashi's text that the end is black (it would have sufficed to cut the black part, and he cut also the red).

From this [the Gemara] infers that he permits Davar she'Eino Miskaven.

Explanation #2 (Rashi): It infers from this that he permits because he does not intend for shearing and working, rather, to fix (be Machshir).

Question: This is unlike other expressions of Ein Miskaven elsewhere, for here he intentionally shears with scissors!

Answer: According to Rashi, we can say that it asks as follows. Does R. Yosi ben ha'Meshulam forbid Davar she'Eino Miskaven, and he permits because Tolesh is not Gozez?

We find regarding Parah that even with scissors, which is Gozez, because he does so in order to be Machshir the Parah, it is permitted. Also regarding Bechor, he should permit in every case! Since he does so for the sake of a proper Shechitah, this is not considered Gozez!

Objection: This is wrong, for in any case one can ask [this], whether the reason is due to Davar she'Eino Miskaven or because Tolesh is not Gozez!

Inference: This entire Sugya proves that shearings of Pesulei ha'Mukdashim are permitted mid'Oraisa;

Even Rabanan, who forbid, the Gemara explains that it is a decree lest one delay [Shechitah, in order to get more shearings].

Implied question: We expound above (6b) "Tizbach" (slaughter Pesulei ha'Mukdashim), and not shearings!

Answer: It means "Tizbach", but do not shear.

Question #1: According to Rebbi, who says in Chulin (35b) regarding "Al ha'Aretz Tishpechenu ka'Mayim", that it comes to permit blood of Pesulei ha'Mukdashim, for one might have thought that since shearing and working them are forbidden, also their blood must be buried. The verse teaches that this is not so;

How could one think to forbid Hana'ah from their blood, because shearing and working are forbidden? Even the shearings themselves are permitted!

Suggestion: It is permitted mid'Oraisa when it fell [by itself], but if he intentionally sheared, it is forbidden.

Rejection #1: This does not answer our question, for intent for blood is like shearings that fell. He does not [slaughter] for the sake of blood, rather, to permit eating the meat!

Rejection #2: They argue even about one who detaches, like is proven below (26a), that Akavya permits. This implies that Rabanan forbid only mid'Rabanan (for they argue about whether or not we decree. Even though there they argue about what fell by itself, Tosfos at the end of Amud B says that we conclude that the laws of Tolesh and Nitlash are the same.)

Rejection #3: Also, even regarding a Tam Olah, the shearings are forbidden only mid'Rabanan, like is proven below (26a) regarding one who was Tolesh wool of a Tam Olah.

Implied question: [The Gemara] asks "[if he was] Tolesh, does anyone permit [the shearings]?!"

Answer: That is mid'Rabanan, like Rashi explained there, because he is a Rasha.

Question #2: In Chulin there, why do we need a verse to permit benefit from blood of Pesulei ha'Mukdashim? Even Kodshim, the blood is Mutar b'Hana'ah from when its Mitzvah was done, and there (Pesulei ha'Mukdashim) there is no Mitzvah. Why should it be forbidden?!

Question #3: Why does it say "since shearing and working are forbidden for them"? After Shechitah one may shear them and work with them, for from Shechitah and onwards everything is permitted. There it discusses blood of Shechitah!

Note: What work can one do with them after Shechitah, i.e. while they are quivering? Perhaps Tosfos holds that milking is considered Avodah with the animal, like R. Gershom (above 6b DH Ela mid'Gali) and Hagahos Mordechai (Shabbos Perek 16, Remez 464 (p.82 in a standard Gemara) DH u'Matzasi); it applies even after death. Below Tosfos says that '"Basar", and not milk' is not an Isur to milk. He did not say that we already know milking due to Avodah. Perhaps the Havah Amina was to learn Avodah from "Basar", like the Ran (Mo'ed Katan 12a DH ka'Yotzei). R. Gershom (above 12a DH Pesulei) learns the Avodah of milking from "Basar"!

Also milk we forbid [only] in its lifetime, but not after Shechitah, according to the opinion that expounds above (15b) "you have a Heter to eat it only from Shechitah and onwards", and not because it says "Basar"!

Further, all permit [milk after Shechitah], since we wanted to learn a Heter for [Chulin] milk above (6b), since the Torah forbade milk of Pesulei ha'Mukdashim, and it did not say that we need the verse for [milk] after Shechitah! (I.e. perhaps all milk is forbidden in the animal's lifetime; we need a verse to forbid milk of Pesulei ha'Mukdashim even after Shechitah, for such milk of Chulin is permitted.)

Answer (to Question #3): However, we can say that we need "Tishpechenu ka'Mayim" due to blood that came out before the majority [of the Simanim] were cut.

Question: However, in any case it is difficult from our Sugya (Question #1. Why do we need Tishpechenu ka'Mayim, lest we learn from shearing and working to forbid blood? Even the shearings themselves are permitted!)

Answer (Tosfos' Rebbi): One might have thought to forbid blood like milk, because we expound "Basar", and not milk, and likewise "Basar", and not blood;

It is unlike shearings, which are permitted, for we learn shearing from "Tizbach", which connotes slaughter, and do not shear (the act of shearing is forbidden, but not the shearings);

However, here it is written v'Achalta Basar, which connotes that you eat meat, but not milk and blood, and it comes to forbid blood even b'Hana'ah, for [the verse] is not needed to forbid eating [blood].

Implied question: The Drashah is not resolved regarding blood like it is for milk, which is permitted to eat!

Note: I.e. the verse permits the meat, but not other parts of the animal. Since it is needed to forbid milk, what is the source to say that it comes to forbid also Hana'ah from blood? And if so, it should likewise forbid Hana'ah from Chelev and Gid ha'Nasheh, and there is no verse to permit them!

Answer: In any case, also blood is edible (so the Drashah applies also to it. Perhaps Tosfos means that one may eat it, i.e. after it is cooked. Even so, there was a Havah Amina to forbid Hana'ah, since one may not eat Stam (uncooked) blood.)

Implied question: Why does it not bring there [that we thought to forbid blood due to] "Basar", and not milk', rather, '"Tizbach", and not shearing'?

Answer #1: It mentioned the beginning of the [Drashah].

Answer #2: [The Gemara] prefers to bring the Isur of shearing, which is stringent even for lashes, like initially, before it became Pasul, like a Beraisa teaches "one who shears or works [with it] receives 40 lashes";

Since the Torah was so stringent, one might have thought to expound the verses to be stringent - '"Basar", and not milk or blood', if not for ["Tishpechenu] ka'Mayim."

Support: It is proven like this above (6b) that what we expound '"Basar", and not milk' is not an Isur to milk. (Rather, it forbids the milk);

Source: We wanted to infer from it a Heter for [Chulin] milk. Since the Torah revealed about Pesulei ha'Mukdashim "Basar", but not milk, this implies that [Chulin] milk is permitted. This shows that the verse comes to forbid milk that was milked.

Observation: In the conclusion of our Sugya, it explains that this is not only Tolesh. The same applies to what became detached [by itself];

It mentioned Tolesh only due to the Seifa, which taught Tolesh due to the Chidush of Akavya (he permits even if one detached).