Question: Since Rav taught (1) that the Halachah follows the Mishnah everywhere in our Perek, why did he need to explicitly say (2) that the Halachah follows R. Yosi?

Answer: Had he taught only (1), one might have thought that he refers only to R. Yosi;

He said "everywhere in our Perek" because R. Yosi taught two laws. He does not refer to R. Shimon, for an argument in a Beraisa is considered an argument.

Now that he explicitly taught that the Halachah follows R. Yosi, we know that "everywhere in our Perek" refers to R. Shimon, for an argument in a Beraisa is not considered an argument.

Question: What is this Beraisa?

Answer (Beraisa): If one buys a nursing mother from a Nochri, the next animal born is a Safek Bechor. It is possible that it is Merachem (has compassion for, i.e. nurses) another animal's child, even though it has not given birth.

Question: R. Shimon ben Gamliel said "it has its Chazakah." What does this mean?

Perhaps it means that an animal will not be Merachem unless it has given birth. However, once it has given birth, it is Merachem (even calves of other animals);

Or, it means that an animal will never nurse a different animal's child!

Question: What difference does it make which he means? (Either way, a nursing animal is exempt from Bechorah!)

Answer: This determines whether or not one is lashed for Oso v'Es Beno (for slaughtering a calf and the animal it nurses from):

If an animal will never nurse a different animal's child, he is lashed;

If a mother is Merachem, he is not lashed.

Answer #1: (Mishnah - R. Shimon ben Gamliel): If one buys an animal from a Nochri, we are not concerned lest it (the calf it nurses) was from another animal.

Rejection: Had it said "(we are not concerned lest it) is (from another animal)," this would have resolved our question. (This would connote that the Mishnah primary discusses the calf - Yad Binyamin);

However, it says "was" (this connotes that the Mishnah primary discusses which calf the mother nursed), i.e. we are not concerned lest the calf is from another animal unless there already was a child to the nursing mother.

Answer #2 (Beraisa): If one entered his herd and found the Mevakros and non-Mevakros nursing, we are not concerned lest a mother is nursing a different animal's calf.

If a mother might be Merachem, we should be concerned!

Rejection: A mother would not abandon her own calf and nurse a different animal's calf.

Answer #3 (Beraisa - R. Shimon ben Gamliel): It has its Chazakah. Similarly...

Suggestion: "Similarly" teaches that the Reisha is just like the Seifa, i.e. the nursing mother definitely gave birth to the suckling calf.

Rejection: No, the Reisha need not resemble the Seifa.

Question: If so, why does it say "similarly"?

Answer: In both cases, the mother is definitely exempt from Bechorah.

(R. Yochanan): If we see a pig cling to and nurse from a ewe, the ewe is exempt from Bechorah. One may not eat the pig "Ad Yavo v'Yoreh Tzedek" (until Eliyahu will tell us that it is permitted.)

Question #1: 'The ewe is exempt from Bechorah' is like R. Shimon. 'One may not eat the pig' is like Chachamim (who say that nursing does not prove motherhood)!

Question #2: "V'Yoreh" connotes teaching a Halachah. If Rabah holds like Chachamim, Eliyahu would not permit it by teaching a law, rather, through telling us what the mother was. If so, R. Yochanan should have said "Ad she'Yivada Lecha Davar"!

Suggestion: R. Yochanan is unsure whether the Halachah follows R. Shimon or Chachamim. (Eliyahu will settle this doubt.)

Rejection #1: Since he exempts the ewe from Bechorah, he must be sure that the Halachah follows R. Shimon!

Rejection #2: R. Yochanan taught that the Halachah follows R. Shimon ben Gamliel in all Mishnayos except for three: the Mishnah of an Arev (guarantor), the Get in Tzidon, and the litigant who found a proof after he said that he does not have one.

Answer (to both questions): Really, he is sure that the Halachah follows R. Shimon;

He is unsure whether or not R. Shimon holds that a mother might be Merachem. One is not lashed for Oso v'Es Beno.

Question: If so, why did he discuss a pig? He should have discussed a ewe nursing a lamb (a normal case);

He should (exempt the ewe from Bechorah, and) say that one who slaughters both of them on the same day is not lashed "Ad Yavo v'Yoreh Tzedek"!

Answer: He must teach about a pig;

Had he taught about a lamb, we would have thought that even if R. Shimon holds that a mother might be Merachem, this is limited to its own species;

Therefore, he taught about a pig, to teach that perhaps R. Shimon holds that a mother is Merachem, even on a different species.

R. Yochanan: Achai b'Ribi asked, if we see a pig cling to and nurse from a ewe, what is the law?

Question: What does he ask about?

Suggestion: He asks about Bechorah, i.e. whether the Halachah follows R. Shimon or Chachamim.

Objection: If so, why did he discuss a pig? He should have discussed a ewe nursing a lamb!

Answer: He asks about (exempting the next child of the ewe from Kedushas) Bechorah, (only) according to Chachamim. He also asks about eating the child, (even) according to R. Shimon. (We now explain these.)

He asks about Bechorah, according to Chachamim. Even though they say that an animal is Merachem, perhaps this is limited to its own species.

He asks about eating, even according to R. Shimon;

If R. Shimon says that a mother might be Merachem. Perhaps this is limited to its own species;

Or, perhaps it might be Merachem even another species!

These questions are unsettled.

(Mishnah - R. Yosi ben ha'Meshulam): One who slaughters a Bechor makes room (for Shechitah) on both sides with a Kopitz (large chopping knife). He uproots the hair, but must not move it. (He should leave it caught in the attached hair, lest it look like he shears. Tosfos Yom Tov - the Mishnah discusses "hair" to teach that shearing applies not only to sheep's wool, but even to hair of cattle. Tosfos Chadashim - it teaches that even though hair is not as disordered as wool and can more easily be moved aside without removing it, even so one may uproot the hair. Mahari'ach - attached wool is called hair. Rashash - "hair" excludes goats' hair (which is called "Notzah"). One may not uproot it, for it is normally sheared by hand.)

Version #1 (our text): Similarly, one uproots hair to inspect a Mum.

Version #2 (text of the Bach and Rishonim, and the Mishnayos): The same applies to one who uproots hair to inspect a Mum. (We adopt this text, for the Gemara (25a) asks whether this is l'Chatchilah.)

(Gemara - Rav): The Halachah follows R. Yosi.

Question: Is this permitted on Yom Tov (to clear away the hair for Shechitah)?

If R. Yosi permits removing hair of a Bechor because uprooting is not considered shearing (and the Torah forbids only shearing a Bechor), he would forbid on Yom Tov (to uproot something from where it grows);

If he holds that uprooting is shearing, and he permits because (and on condition that) it is a Davar she'Eino Miskaven (he does not intend to uproot hair, only to clear it away), this is similarly permitted on Yom Tov.

Rav Huna: Ask Rav Chananel. If he says that Rav rules like R. Yosi, I will answer your question.

(Rav Chananel citing Rav): The Halachah follows R. Yosi.

Answer (Rav Huna): It is permitted on Yom Tov.

Support: Also R. Chananya said so in the name of Rav.