If it serves to exclude a case where a female emerged from the womb before it, that is derived from the phrase “that which opens any womb.” Rather, conclude from it that “firstborn” serves to exclude a case where an animal emerged from the womb after its older sibling was born by caesarean section. According to Ravina, the word “firstborn” is referring to an animal that is a firstborn even in only one aspect, but as it is extraneous it serves to exclude an animal whose older sibling was born by caesarean section.

Rav Aḥa of Difti said to Ravina: If it enters your mind that a firstborn in one aspect is called a firstborn and the derivation is based on the fact that the term “firstborn” is superfluous, that works out well in a case where a male emerged by caesarean section and then another male emerged through the womb. It stands to reason that it is not sanctified, as this birth is excluded by the word “firstborn,” as it is the firstborn of the womb, but it is not the firstborn of the males.

But in a case where a female emerged by caesarean section and afterward a male was born through the womb, let it be sanctified, as it is the firstborn of the males and the firstborn of the womb. One cannot derive the exclusions of both of these cases from the word “firstborn,” and yet the baraita indicates that even if a female was born first by caesarean section, the male born afterward is not considered the firstborn. The Gemara concludes: Rather, it is clear that the baraita must be interpreted in accordance with the explanation of Abaye, that a firstborn in one aspect is not called a firstborn.

MISHNA: In the case of one who purchases a female animal from a gentile and does not know whether it had previously given birth or whether it had not previously given birth, and after the purchase the animal gave birth to a male, Rabbi Yishmael says: If the mother was a goat within its first year the male offspring certainly is given to the priest, as it definitely never gave birth previously. From that point forward, i.e., if the mother is older than that, its offspring’s status as a firstborn is uncertain. If it was a ewe within its second year the male offspring certainly is given to the priest; from that point forward an offspring’s status is uncertain. If it was a cow or a donkey within its third year the male offspring certainly is given to the priest; from that point forward the offspring’s status is uncertain.

Rabbi Akiva said to him: 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 Sages said: An indication of the offspring in a small animal is a murky discharge from the womb, which indicates the animal had been pregnant, and therefore exempts subsequent births from the mitzva of the firstborn. 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. Since these can be produced even within a year, it cannot be assumed that an animal in its first year is definitely subject to the mitzva of the firstborn.

Rabbi Akiva continues: Rather, this is the principle: 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.

GEMARA: The mishna teaches that according to Rabbi Yishmael, the firstborn status of the offspring of a goat acquired from a gentile when it was more than one year old is uncertain. The Gemara asks: From that point forward, i.e., if it was bought after its first year, why is it in a state of uncertainty? One should follow the majority of animals, and as the majority of animals are impregnated and give birth within their first year, it can be assumed this animal certainly gave birth. The Gemara suggests: Shall we say Rabbi Yishmael holds in accordance with the opinion of Rabbi Meir, who says one must be concerned for the minority, i.e., he must take the minority of cases into account?

The Gemara responds: You may even say Rabbi Yishmael holds in accordance with the opinion of the Rabbis. When the Rabbis follow the majority, this is in a case of an evident majority, which is extant and can be examined. For example, in a situation where a piece of meat is found in front of nine stores selling kosher meat and one store selling non-kosher meat, and it is not known from which store it came, it may be assumed that it came from one of the stores that sells kosher meat. And similarly, the Sanhedrin reaches its decisions by a majority vote of its judges. But with regard to a non-evident majority, which is based solely upon statistical information such as the assertion that most animals become pregnant and give birth within their first year, even the Rabbis do not follow the majority.

The Gemara raises a difficulty: But the case of levirate marriage of a male minor or a female minor is dependent upon a non-evident majority, and yet the Rabbis follow the majority in their ruling. As we learned in a baraita: A male minor or a female minor may not perform the ritual through which a yavam frees a yevama of her levirate bonds [ḥalitza], nor enter into levirate marriage; this is the statement of Rabbi Meir. The Rabbis said to Rabbi Meir: You have aptly stated that they may not perform ḥalitza, since “man,” indicating an adult male, is written in the section of the Torah addressing ḥalitza (see Deuteronomy 25:7). Although an adult female is not mentioned explicitly, we juxtapose the halakha of the woman to that of the man and require that the female involved in ḥalitza must be an adult as well.

But what is the reason they may not enter into levirate marriage, with regard to which the Torah’s wording does not specifically indicate adults? Rabbi Meir said to them: In the case of a male minor I am concerned lest he is found to be a eunuch, i.e., one who is incapable of fathering children, when he grows up. Similarly, a female minor may not enter into levirate marriage lest when she grows up she is found to be a sexually underdeveloped woman [ailonit], who is incapable of bearing children. In either case the mitzva of levirate marriage does not apply, and they would be found to have encountered a forbidden relative and entered into a forbidden relationship where no mitzva applies, as the entire purpose of levirate marriage is to have children for the brother who died childless.

And the Rabbis hold: Follow the majority of male minors, and most male minors are not eunuchs; and likewise, follow the majority of female minors, and most female minors are not sexually underdeveloped women. This indicates that the Rabbis disagree with Rabbi Meir even with regard to a non-evident majority.

Rather, Rava says: