I heard that if we do not have a messora on a certain bird but we do have one on a similar species then we can check by checking if their offspring can have offspring

What is this idea based on?
I remember hearing something similar in a day yomi shiur but can not find it now.

  • 1
    It seems (from Rav Shechter in video linked) that it is sefaria.org/Bekhorot.7a.31 and end of pischai teshuva y"d 82.1 beta.hebrewbooks.org/tursa.aspx?a=yd_x4192
    – hazoriz
    Oct 18, 2017 at 0:53
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    The gemara you cite seems to pretty explicitly indicate that even impregnation by a kosher species is enough to indicate kashruth. No need for even a viable birth, let alone a third generation. (Notably, impregnation is a tall order for birds;)
    – Loewian
    Oct 18, 2017 at 2:07
  • @Loewian (first I asked then I found the above sources, I did not delete the question because it got 2 +1s) btw you can candle an egg for example youtu.be/hoMWDuk7vKc
    – hazoriz
    Oct 18, 2017 at 2:40

1 Answer 1


Your looking for Chullin 62a

זרזיר הוא מין עורב שכן נאמר בעורב למינו להביא את הזרזיר

Kesef Mishne on Rambam hilchos Maacholos Assuros 1,20 says that 2 things are required for it to be considered a non-kosher bird according to the Rambam. If it is both similar and lives together with that species of definite non kosher bird e.g raven.
דזרזיר אף לחכמים טמא שהוא שכן ונדמה ולא נחלקו אלא בטעם טומאתו דלרבנן אע"פ שהוא שכן לא היו מטמאים אותו אילו לא היה נדמה

Note: This is not a ruling as it is a complicated subject that requires considerable authority to deal with.

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