An [animal] born by Caesarean section and the one that follows it —- R’ Tarfon says: Both must be left to pasture until they develop blemishes, and they may be eaten with their blemish by their owner. R’ Akiva says: Neither one is a bechor; the first, because it did not open the womb, and the second, because it was preceded by another.

[If] one buys an animal from a non-Jew, and it is not known whether it had borne its first [offspring] or not —- R’ Yishmael says: [The offspring of] a goat in its first year certainly belongs to a Kohen, from here on it is questionable; [the offspring of] a ewe in its second year certainly belongs to a Kohen, from here on it is questionable; [the offspring of] a cow or donkey in its third year certainly belongs to a Kohen, from here on it is questionable. R’ Akiva said to him: If offspring alone would exempt the animal, it would be as you say; but they said: The sign of offspring in small livestock [is] a womb-discharge; and in large livestock, an amniotic sac; and in a woman, an embryo or an amnioti sac. This is the rule: [With] any [animal] known to have previously borne its first, the Kohen receives nothing; and [with] any one that had not borne its first, this [first male offspring] belongs to the Kohen; if it is questionable, it may be eaten in its blemished [state] by the owner.  R’ Eliezer ben Yaakov says: [If] a large livestock animal discharges a mass of congealed blood, it must be buried, and it is exempt from the laws of bechor.