Gemara

(Mishnah): One tears the udder to remove the milk. If it was not torn, one (who eats it) does not transgress.

One tears the heart to remove the blood. If it was not torn, he does not transgress.

Version #1 (Rav): (If the udder was not torn,) he does not transgress, and it is permitted.

Even though the Reisha says 'he does not transgress', which connotes that it is forbidden, this is only for parallel structure with the Seifa.

Support (Beraisa): One tears the udder to remove the milk. If it was not torn, he does not transgress.

One tears the heart to remove the blood. If he did not tear it, he tears it after cooking it, and it is permitted.

Inference: The udder is permitted without tearing it!

Rejection: Tearing after cooking helps only for the heart, but not for the udder.

Version #2 (Rav): (If the udder was not torn,) he does not transgress, but it is forbidden.

The Gemara supports and challenges this from the Mishnah and Beraisa, and dispels them, like above.

Support (for Rav, according to Version #1 - Beraisa): If an udder was cooked with its milk inside, it is permitted;

If a stomach was cooked with the milk inside (that the animal suckled), it is forbidden.

This is because the milk in the stomach was gathered after it left (the mother's udder). The milk in the udder never left. It was never considered milk.

(Rav Yehudah): We tear the udder lengthwise and widthwise, and press it against the wall.

R. Elazar (to his servant): Tear the udder, and I will eat it.

Question: Why did he need to say this? The Mishnah teaches this!

Answer (#1): He shows that one need not tear it lengthwise and widthwise...

(Some texts - Answer #2: He teaches that this (tearing it) permits cooking it even (with other meat) in a pot.)

Yalsa (Rav Nachman's wife): For everything that the Torah forbids, something similar is permitted. I want to eat meat and milk!

Rav Nachman (to a butcher): Roast an udder for her.

Question: The Mishnah says that one must tear it first to remove the milk!

Answer: That is if one wants to cook it.

Question (Beraisa): If an udder was cooked with its milk inside, it is permitted.

That is only b'Di'eved!

Answer: It is even l'Chatchilah. Since the Seifa discusses a stomach that was cooked with the milk inside, also the Reisha says 'was cooked'.

111a - Version #1: If liver was roasted on the same spit with other meat, and the liver was above, both are permitted;

This is because blood (that drips from the liver) is slippery. It slides off the meat. It is not absorbed;

If udder was roasted on a spit with other meat, and the udder was above, the meat is forbidden.

This is because milk (that excludes from the udder) clings and is absorbed in the meat.

Version #2 (Rav Dimi or Neharda'a): If udder was above other meat (roasting on the same spit), both are permitted. Chachamim were lenient because the Isur of milk from a slaughtered cow (cooked with meat) is only mid'Rabanan;

If liver was above other meat, the meat is forbidden;

Because the Torah forbids blood, we are stringent. (end of Version #2)

Mereimar: The laws of udder and liver are the same. L'Chatchilah, they may be roasted under other meat, but not above. B'Di'eved, if they were roasted above, all is permitted.

Rishonim

Rif (38b): The Halachah is, one may roast udder even if it was not torn at all, like Rav Nachman said to roast for Yalsa.

Rambam (Hilchos Ma'achalos Asuros 9:12): Udder is forbidden mid'Rabanan. If one tore it and cleaned off the milk, one may roast it and eat it

Rambam (14): (Even) if udder was cut, one may not roast it on a spit above meat. If it was roasted, everything is permitted.

Rosh (8:24): Rashi connotes that our Sugya discusses roasting udder. It cannot discuss cooking, for then the milk would be reabsorbed. If the udder was torn slightly, l'Chatchilah one may roast it, for the milk is not gathered inside. Even though it gets absorbed again, Chachamim did not decree, for there is no (other) meat with it, and the absorption did not change the udder's taste. Therefore, we do not decree due to meat and milk. Even when one did not tear it, l'Chatchilah one may roast it.

Rosh (27 DH Darish): Mereimar taught that l'Chatchilah, one may roast udder or liver under other meat. If they were roasted above, they are permitted b'Di'eved, but l'Chatchilah this is forbidden. Rashi says that l'Chatchilah one may not roast on our spits, for there is no difference between above and below. Sometimes we raise the end of the spit near the fire and sometimes we lower it. Why does the Gemara permit udder under meat? The fat of the meat drips on the udder, and clings to it! Do not say that we tore it lengthwise and widthwise and pressed it against the wall. If so, it is permitted even above meat, for one may cook it in a pot with meat! Rather, here is worse. Even though he tore it, milk of the udder drips on the meat, and it is evident that it is milk. We always permit salting udder with meat, for salt does not cause milk to exude. Also, milk is not absorbed in the walls of the udder. Rather, it is gathered in the inside. We can learn from here a clear Heter, that after it was torn lengthwise and widthwise and pressed against the wall, one may cook it with meat l'Chatchilah. We learn from the Heter to roast it under meat, even though the fat of the meat drips on the udder. This is unlike those who are careful not to cut udder with a hot meaty knife. We permit even on one spit (with meat above) l'Chatchilah!

Mordechai (745): A case occurred in which udder and meat were salted together in a Kli with holes. They delayed there the time for salting, and afterwards they were put in a Kli without holes. Maharam permitted both of them.

Taz (13): Torah Chatas says that he needed to say that the first Kli had holes due to the blood of the udder and meat, but not for the milk.

Poskim

Shulchan Aruch (YD 90:2): The custom is to roast udder only after tearing it lengthwise and widthwise.

Beis Yosef (DH Ha): Any amount of tearing suffices for roasting, because the milk drips down. One must tear it lengthwise and widthwise only to cook it in a pot. The Beraisa permits if it was cooked (with its milk inside), i.e. if it was roasted. Roasting is also called cooking ("va'Yevashlu ha'Pesach"). Rav Nachman holds like Version #2, and establishes the Beraisa to discuss when it was roasted.

Beis Yosef (DH veha'Ran): Even though the Rif permits roasting without any tearing, the Ran holds that l'Chatchilah one should tear it a little, like R. Tam says.

Beis Yosef (DH u'Mah she'Chasav ul'Tzli): Tosfos, the Rosh, Sefer ha'Terumah and R. Yerucham say that Rashi requires tearing lengthwise and widthwise for roasting. What is the reason? R. Elazar teaches that any amount suffices! It seems that he does not argue with Rav Yehudah, for Rav Yehudah discusses cooking! Indeed, the Ran holds that Rashi holds that any amount of tearing suffices. It is difficult to say that the others hold that Rashi requires lengthwise or widthwise. The Rashba says that Rashi explains that the entire Sugya discusses roasting. This is difficult. If so, he should require also pressing against the wall, like Rav Yehudah said!

Rema: The custom is to tear it lengthwise and widthwise, and press it against the wall before roasting it. If one transgressed and roasted it without tearing it, it is permitted if it was roasted alone without other meat.

Gra (17): This is like Version #1, for a Beraisa supports it.

Rema: If it was roasted with other meat, if it was torn lengthwise and widthwise, and pressed against the wall, both are permitted.

Shach (11): Even if we know that the spit flipped (and the udder was on top), since it was torn lengthwise and widthwise and pressed against the wall, it is like regular meat for this.

Gra (18): If he did not tear it lengthwise and widthwise, and press it against the wall, the udder is forbidden b'Di'eved if it was under the meat, and all the more so the meat is forbidden if it was under the udder.

Rema: If not, the top one is permitted, and the bottom one is forbidden. We do not forbid both due to concern lest the spit was reversed. B'Di'eved, we do not make assumptions to create Isurim. L'Chatchilah, one should not roast it with meat at all.

Shach (12): If we know that they were on equal heights on the spit, they are permitted.

Shach (13): This is because our spits are horizontal, and sometimes one end is above, and sometimes the other end.

Shulchan Aruch (4): The laws of roasting udder or salting it with meat are like the laws of roasting liver or salting it with meat. Some permit to salt udder over meat.

Shach (25): The Mechaber permits l'Chatchilah only when the udder is underneath, and with our spits, not at all. B'Di'eved, even if the udder was on top it is permitted. The Rema gave his opinion above (in Sa'if 2).

Beis Yosef (DH Ba): Tosfos and the Rosh say that we permit roasting udder under the meat after it was torn. Rashi forbids with our spits, for there is no difference between above and below. He said so regarding liver, but surely the same applies to udder. With did the Tur bring this only regarding liver? Mereimar equated udder and liver!

Beis Yosef (DH v'Chasav): The Rashba says that the same applies to salting with meat, for salting is like roasting. The Rosh permits, for salt does not cause milk to exude, and milk is not absorbed in the walls of the udder.