Question: What is the Gemara asking? It is specifically the Isur of Yom Kipur that does not take effect on that of Neveilah, but the Isur of Nosar does take effect on that of Cheilev.

Reason: Since Neveilah and T'reifah take effect on Cheilev, as the Gemara says in Perek ha'Shochet (Chulin, Daf 37a) - Kal va'Chomer Nosar, which is more stringent than Neveilah, should certainly take effect on the Isur of Cheilev?

Answer: He holds that since we see that Yom Kipur, which is a stringent Isur, does not take effect on a lighter one, by the same token Nosar which is also strict, will not take effect on Cheilev, despite the fact that it (Cheilev) has a Heter (by a Chayah) See Olas Sh'lomoh.

Question #1: What is the Kashya? Perhaps Yom Kipur is different, inasmuch as it does not take effect on Neveilah - because it is only an Isur Kollel, whereas here by Nosar, it is an Isur Mosif (See Olas Shlomoh) ...

Question #1 (cont.): And we will say that even though Rebbi Shimon does not hold Isur Kollel, he does hold Isur Mosif? ...

Precedent #1: Indeed, we find this by Rebbi Yossi, who does not hold Isur Kollel, but he does hold Isur Mosif.

Introduction to Question #2: The same Kashya will apply in Perek Asarah Yuchsin (Kidushin, Daf 77b & 78a), where it says that 'If a Kohen Gadol has relations with his sister who is an Almanah the Isur Almanah does not take effect on that of Achoso' ...

Introduction to Question #2 (cont.): And Rav Sheishes establishes the author as Rebbi Shimon, who holds 'Ein Isur Chal al Isur' ...

Introduction to Question #2 (concl.): As we learned in a Beraisa 'Someone who eats Neveilah on Yom Kipur, is Patur' ...

Question #2: What is the proof from there? Perhaps Yom Kipur, which is (only) an Isur Kollel, is different; but by Isur Mosif, Rebbi Shimon will concede (that it takes effect)?

Precedent: Like Rebbi Yossi, who does not hold Isur Kollel, as in the case of 'Chamoso she'Na'asis Eishes Ish', yet the Gemara says that 'Rebbi Yossi concedes by Isur Mosif'.

Answer: The Gemara knew that Rebbi Shimon does not even hold Isur Mosif ...

Source: From the Beraisa in Perek Arba'ah Achin (Yevamos (32a) 'Someone who has relations with the wife of his brother who is also the sister of his wife, is Chayav only one Chatas, irrespective of whether the deceased man married her and then the living one, or vice-versa' (Eishes Ach is an Isur Mosif - See Sugya there).

Question: In that case, why does the Gemara, both here and there in Kidushin, not mention this?

Answer: It is speaking here where one Isur is Chamur and the other, Kal (See Birchas ha'Zevach).

Implied Question: And if you will ask that here there is an Isur Mosif by Nosar and an Isur Kollel by Yom Kipur ...

Answer: What the Gemara is saying is - Even if we find that Rebbi Shimon does not hold Isur Kollel, whether by an Isur Kal or by an Isur Chamur, we also find that, generally, he does not hold Isur Mosif ...

Answer (cont.): In which case, he will not hold of mit even by an Isur Chamur on an Isur Kal ...

Answer (concl.): Then why is Isur Nosar effective on Isur Cheilev - which is lenient because it has a Heter?

Precedent: And likewise in Perek Asarah Yuchsin (Ibid.) the Gemara needs to prove that an Isur Chamur does not take effect on an Isur Kal

Precedent (cont.): Because it learns it there on account of the second Lashon, and due to it, it cites it even according to the first Lashon.

Question: Rabeinu Elchanan asks that we need the Pasuk "asher la'Hashem" to Darshen that 'One is only Chayav because of Tum'ah on whatever is permitted to Tehorim' (Menachos, Daf 25b. [See Shitah Mekubetzes 19]).

Answer: Since both D'rashos are equally feasible, we learn them both from the same Pasuk (See also Tosfos, Menachos, 25b DH 'Talmud Lomar').

Clarification: Since the Isur Cheilev and that of Me'ilah come simultaneously.

Implied Question: And although there is no Me'ilah by Kodshim Kalim until after the Zerikah ...

Source: As we learned in the Mishnah in Me'ilah (Daf 7b) ...

Answer: Nevertheless, an Isur there is.

Question: The Isur Cheilev comes into effect earlier - when it is still in its mother's womb? ...

Source: For so Rebbi Yochanan says in Perek Beheimah ha'Maksheh (Chulin, Daf 75a) - 'If he tore detached Cheilev from a live nine-month animal, its Cheilev is like that of a live animal, since the criterion lies in months and not in air (being born)'.

Answer: Granted, we do not need the animal to have come out into the world, we do however, need the Cheilev to have come out, but as long as it is still in the its mother's womb, the Isur does not take effect.

Clarification: It does not say that 'He should bring an Olah with its proceeds, as that would imply that he brings the Nesachim from his own pocket ...

Clarification (cont.): But that it goes 'to Nenavah' - that buys with its proceeds an Olah, but that the Nesachim come from the communal funds.

Reason: Since the leftovers of an Asham go to Kayitz ha'Mizbe'ach, which is why he brings an Olah - (which Kayitz ha'Mizbe'ach is, and the Nesachim come from communal funds - Shitah Mekubetzes quoting the Rosh).

Clarification (Rebbi Meir): This goes nicely according to Rebbi Meir, who holds that they are Chulin in the Azarah ...

Clarification (Rabanan #1): But even according to the Rabanan, who say that one makes from it an Olas Nedavah, that is from the proceeds, but they concede that the Asham itself is a Pasul Korban, and it is not acceptable.

Clarification (Rabanan #2: Alternatively, since at the time of Shechitah it was not eligible to be brought as an Olah, seeing as he did not yet know (that he sinned), he cannot bring it as an Olah after the Shechitah.