It is clear, as was suggested initially, that Rabbi Yishmael holds in accordance with the opinion of Rabbi Meir, who says that one must be concerned for the minority.

Ravina says: You may even say that Rabbi Yishmael holds in accordance with the opinion of the Rabbis. When the Rabbis follow the majority, it is with regard to a majority that is not dependent upon an action but is simply the nature of reality. But in the case of a majority that is dependent upon an action, such as the pregnancy of a young goat, which depends upon whether or not it had copulated with a male, the Rabbis do not follow the majority.

§ The Sages taught in a baraita: If one purchased a goat within its first year from a gentile and does not know whether or not it had previously given birth, the subsequent male offspring certainly is given to the priest; from that point forward an offspring’s status as a firstborn is uncertain. If it was a ewe within its second year the offspring certainly is given to the priest; from that point forward an offspring’s status as a firstborn is uncertain. If it was a cow within its third year the offspring certainly is given to the priest; from that point forward an offspring’s status as a firstborn is uncertain. If it was a donkey it is subject to the same halakha as a cow. Rabbi Yosei, son of Rabbi Yehuda, says: The offspring of a donkey within its fourth year also has the status of a firstborn. Until here is the statement of Rabbi Yishmael.

The baraita continues: When these matters were stated by the students before Rabbi Yehoshua, he said to them: Go out and say to Rabbi Yishmael: You erred. Were an animal exempted only by giving birth to an offspring and in no other manner the halakha would be in accordance with your statement. But the Rabbis said: An indication of the offspring in a small animal is a murky discharge from the womb, which exempts subsequent births from the mitzva of the firstborn. And the indication in a large animal is the emergence of an afterbirth, and the indication in a woman is a fetal sac or an afterbirth.

Rabbi Yehoshua added: That is the opinion of the Rabbis, but I myself do not say so. Rather, I hold that a goat that expelled a murky discharge from the womb at the age of six months can give birth within its first year, and a ewe that expelled a murky discharge in its first year can give birth within its second year. The Gemara will later discuss the practical difference between his opinion and the ruling that he ascribes to the Rabbis. Rabbi Akiva says: I have not arrived at this method of determining firstborn status. Rather, in any case where it is known that the animal had previously given birth, the priest has nothing here. And in any case where it is known that the animal had not previously given birth, that is given to the priest. And if it is uncertain, it may be eaten in its blemished state by the owner.

The Gemara analyzes the baraita. With regard to what matter do Rabbi Yishmael and Rabbi Yehoshua disagree? Shall we say they disagree with regard to whether or not a murky discharge from the womb exempts an animal from the mitzva of the firstborn; as Rabbi Yishmael holds that a murky discharge does not exempt an animal because it is not a sign of a birth, and Rabbi Yehoshua holds that a murky discharge exempts an animal?

The Gemara rejects this suggestion: If we actually see a murky discharge, everyone agrees that the murky discharge exempts an animal. And here, it is with regard to whether one is concerned about the possibility that an animal might have expelled a murky discharge that they disagree. Rabbi Yishmael holds that we are not concerned about a murky discharge, and it can therefore be assumed that the first offspring born after its purchase from the gentile is firstborn; and Rabbi Yehoshua holds that one is concerned about a murky discharge, and due to the uncertainty the next offspring remains with its owner.

The Gemara objects: And is it correct that Rabbi Yishmael is not concerned about the possibility that the mother might have expelled a murky discharge before giving birth to a live offspring? But doesn’t Rava say: It is clear that Rabbi Yishmael holds in accordance with the opinion of Rabbi Meir, who says one must be concerned for the minority? If so, Rabbi Yishmael should be concerned for a murky discharge as well. The Gemara explains: Where Rabbi Yishmael is concerned is when the concern leads to a stringency. But if the concern would lead to a leniency, as in this case, where it would mean that the animal born after a year is only an uncertain firstborn, he is not concerned.

And if you wish, say instead: Whether it leads to a leniency or whether it leads to a stringency Rabbi Yishmael is concerned, and here they disagree with regard to whether or not an animal can expel a murky discharge and then return to its fertile state and give birth within its first year. As Rabbi Yishmael holds: An animal that expels a murky discharge does not return to its fertile state and give birth within its first year, and accordingly, from the fact that this animal gave birth it can be concluded that it certainly did not expel a murky discharge beforehand. And Rabbi Yehoshua holds: An animal that expels a murky discharge returns to its fertile state and can give birth within its first year.

§ The baraita teaches that Rabbi Yehoshua said: That is the opinion of the Rabbis, but I myself do not say so. Rather, I hold that a goat that expelled a murky discharge from the womb at the age of six months still gives birth within its first year, while a ewe that expelled a murky discharge in its first year still gives birth within its second year. The Gemara asks: Since according to both opinions an animal that expelled a murky discharge can still give birth within a year, what difference is there between Rabbi Yehoshua’s tradition of the opinion of the Rabbis and his own reasoning?

The Gemara answers: The difference between their opinions is in a case where a goat expelled a murky discharge at the end of its first six months of life, when the seventh month began, and then gave birth before the end of its first year. And there is a difference between them with regard to the statement of Ze’eiri, as Ze’eiri says: The expulsion of a murky discharge, which is sufficient to exempt an animal from having its future offspring counted a firstborn, prevents it from being impregnated for no less than thirty days. If an animal becomes pregnant within thirty days of expelling a murky discharge, evidently that discharge was not the sign of a fetus, and therefore the offspring will have firstborn status.

In this case, as the pregnancy of a goat lasts five months and a murky discharge was expelled at the end of the sixth month, a goat that gave birth by the end of the year, i.e., twelve months, must have become pregnant within a month of the discharge. The Rabbis, whose opinion Rabbi Yehoshua cited by tradition, accept the statement of Ze’eiri, and therefore they rule that this goat, which became pregnant within a month of the discharge, is not exempt from the mitzva of the firstborn. According to Rabbi Yehoshua’s own reasoning, he does not accept the statement of Ze’eiri, which means that although this animal became pregnant within a month of the discharge, it was nevertheless exempt from the mitzva of the firstborn.

The Gemara suggests another answer: And if you wish, say that everyone accepts the statement of Ze’eiri; and here, in the case of a goat that gave birth within its first year after having expelled a murky discharge at the end of its sixth month, they disagree with regard to whether or not an animal gives birth after incomplete months, i.e., prematurely.