The Gemara adds: And in fact it is taught in a baraita that Rabbi Shimon ben Yehuda says in the name of Rabbi Shimon: An animal whose time has not yet arrived enters the pen to be tithed. And these animals are like a firstborn: Just as a firstborn is consecrated before its time and is sacrificed after its time, so too, an animal whose time has not yet arrived is consecrated before its time and sacrificed after its time.

The Gemara raises a difficulty: But rather than deriving the halakha of tithed animals from the firstborn let one derive it from sacrificial animals, which cannot be consecrated before their time arrives. The Gemara answers that it is reasonable to claim it would be appropriate for one to derive the halakha of tithed animals from the firstborn, as they have the following four aspects in common: First, unlike sacrificial animals, one cannot redeem a firstborn or a tithed animal even if it develops a blemish. Second, a blemish does not prevent them from being imbued with sanctity. Third, an animal that was rendered a substitute for a firstborn or a tithed animal is not sacrificed. Finally, they are consumed without having been redeemed, whereas other sacrificial animals must be redeemed first.

The Gemara responds: On the contrary, it would be appropriate for one to derive the halakha of tithed animals from sacrificial animals, as they have the following in common: First, unlike firstborn animals, both tithed and consecrated animals are not limited to males. Second, both are sanctified by human action rather than intrinsically consecrated. Additionally, they are not included among the gifts to the priest. Finally, both begin life as regular animals rather than as animals with the unique status of being born first. The Gemara accepts this objection: Rather, Rabbi Shimon derives the halakha from a verbal analogy between the term: “You shall pass” (Exodus 13:12), written with regard to the firstborn, and the term: “Whatsoever passes under the rod” (Leviticus 27:32), stated with regard to tithed animals.

§ The mishna teaches that a murky discharge is evidence of an offspring and exempts any future offspring from being counted a firstborn. The Gemara asks: What is considered a murky discharge that exempts future offspring from firstborn status? Rava says: As the shepherds say: A murky [detzalta] discharge from the womb is an indicator of a fetus that the animal suppressed in its womb. And Shmuel says: It is bubbles of blood. The Gemara adds: And one must show the discharge to a Sage [ḥakham] in order to determine its status. The Gemara asks: A Sage? From where would he know how to determine its nature? Rav Pappa says: The reference is to a knowledgeable [ḥakham] shepherd, who is familiar with the different types of discharge an animal can produce.

Rav Ḥisda says: They said the formation of a fetus in a woman takes forty days. Rav Ḥisda therefore asks: In an animal, how many days does it take for the fetus to form? Rav Pappa said to Abaye: Isn’t this question resolved by that which Ze’eiri said, as Ze’eiri said: A murky discharge occurs no less than thirty days after conception? The Gemara explains: No; that was stated with regard to the thirty days after expulsion of a murky discharge, during which a female does not show receptivity to a male and does not become pregnant. The Gemara leaves Rav Ḥisda’s inquiry unresolved.

§ We found that the mishna discusses the halakha of one who purchases an animal from a gentile. The Gemara asks: What is the halakha with regard to one who purchases an animal from a Jew and it is unknown whether the animal had previously given birth? Rav says: Its offspring is a definite firstborn, as if it is so that it had previously given birth to a firstborn, the owner would have boasted to the buyer about the fact that he would not have to give its offspring to a priest.

And Shmuel says: The firstborn status of its offspring is uncertain, as even if it had previously given birth the seller thinks the buyer wants it for slaughter, and therefore he does not bother informing him of its status. And Rabbi Yoḥanan says: Its offspring is certainly a non-sacred animal. What is the reason? If it is so that it had not previously given birth, since there is a prohibition involved, it can be assumed that the seller would have notified the buyer of the animal’s status.

The Gemara notes: It is taught in a baraita in accordance with the opinion of Rabbi Yoḥanan, who says the offspring is non-sacred: With regard to the prohibition against slaughtering a mother and its offspring in the same day, if the seller did not inform the buyer that the mother or offspring of the animal he is purchasing was sold earlier that day, the buyer may go and slaughter the animal and he need not refrain from doing so. Shall we say this baraita is a conclusive refutation of the opinions of Rav and Shmuel? The Gemara rejects this suggestion: There, with regard to slaughtering a mother and its offspring, the matter is dependent upon the seller, as it is his responsibility to notify the buyer. Here, in the case of a firstborn, the matter is dependent upon the buyer, and it is his responsibility to inquire about the animal’s status.

MISHNA: Rabbi Eliezer ben Ya’akov says: In the case of a large animal that expelled a mass of congealed blood, that mass must be buried. The reason is that perhaps there was a male fetus there which was consecrated as a firstborn when it emerged, and the animal is exempt from having any future offspring counted a firstborn.

GEMARA: Rabbi Ḥiyya teaches: That mass of congealed blood does not impart ritual impurity, neither through physical contact nor through carrying it. The Gemara asks: But since does not impart impurity, neither through contact nor through carrying, which indicates that it is not considered a fetus, why must it be buried?