If one buys an animal from a non-Jew and it is not known whether it had given birth or had not given birth: Rabbi Ishmael says: that born of a goat in its first year certainly belongs to the priest; after that, it is a questionable case [of a first-born]. That born of a ewe two years old certainly belongs to the priest; after that, it is a questionable case [of a first born]. That born of a cow or a donkey three years old certainly belongs to the priest; after that, it is a questionable case [of a first born]. Rabbi Akiva to him: if an animal were exempted [from the law of the first born] only with the birth of [actual] offspring, it would be as you say. But they said: the sign of offspring in small cattle is a discharge [from the womb]. In large cattle, the after-birth; in a woman, the signs are the fetus and the after-birth. This is the general rule: Whenever it is known that it had given birth, the priest receives nothing. Whenever it had never given birth, it belongs to the priest. If there is a doubt, it shall be eaten blemished by the owners. Rabbi Eliezer ben Jacob says: if a large domestic animal has discharged a clot of blood, it [the clot] shall be buried, and it [the mother] is exempted from the law of the first born.