Eggs of Kosher Birds
ביצים טהורות
Eggs of kosher birds are permitted to be eaten, and eggs of non-kosher birds are forbidden to be eaten, for “that which comes from the impure is impure, and that which comes from the pure is pure” (Bekhorot 5b). The chicken eggs we normally eat may be bought from anyone, since eggs of non-kosher birds are not found among us, and consequently all eggs that resemble the ordinary eggs we consume have a presumption of kashrut (SA YD 86:2).
If the eggs are different from ordinary eggs, the Sages said (Ḥullin 64a) that if both ends of the egg are round, that is, spherical like a ball, or both are pointed, that is, elongated, or if the yolk (the yellow) is on the outside and the white is on the inside, it is certainly the egg of a non-kosher bird and it is forbidden to eat it. Even if the seller says that it is from a kosher bird, he is not believed. But if one end is round and the other pointed, and the yolk is inside and the white outside, it may be from a kosher bird; in that case, if a person who understands halakha says that it is from a kosher bird, we rely on him and the egg is kosher. If he is considered a trustworthy person but does not understand halakha, the egg is kosher only if he says that it is from a particular species of bird known to be kosher (see Rema and SA YD 86:1).
Eggs laid by a female bird that became a tereifa as a result of an injury or illness are forbidden to be eaten; just as its meat is forbidden, so too its eggs are forbidden. Likewise, an egg found inside a neveila is forbidden to be eaten.¹ One may not place an egg of a tereifa or neveila under a hen to brood on it, lest people mistakenly eat it. But if one did place it and a chick hatched from it, the chick is kosher (SA YD 86:7; Pitḥei Teshuva 4).
Eggs found inside another female bird that was slaughtered in a kosher manner are kosher. If they already have a white and a yolk, they have the status of eggs, which are parve, and one may eat them with milk. If they do not yet have a white, they have the status of meat and one may not eat them with milk (SA YD 87:5).
Notes (1)
- It is explained in Mishna Eduyot 5:1, according to Beit Hillel, that a fully formed egg found inside a neveila is permitted by Torah law, since its formation took place while the bird was kosher, but the Sages forbade it because it came out of a neveila, which is forbidden by Torah law. An egg of a tereifa, which the mother laid some time after becoming a tereifa, is forbidden by Torah law, since part of its formation took place inside a tereifa. Therefore, an egg that may be from a neveila or may be from a kosher bird is permitted, in accordance with the rule of a rabbinic doubt (safek de-rabbanan); but if it may be from a tereifa, it is forbidden, in accordance with the rule of a Torah doubt (safek de-oraita) (SA YD 86:3). If the egg was laid immediately after the mother became a tereifa, even though its prohibition is rabbinic, it is treated as a Torah prohibition, where a doubt is forbidden, because the Sages did not make their rulings dependent on measurements (BY 86:3; Torat Ḥatat 71:1).