This is Tuesday's episode. || How do we know that a chicken has laid an egg? The Gemara connects laying/bearing with the time of conception, at least, in principle. The practical implications here are a little hard to bring to bear. Note also the implications of a male rooster being present. And how many barriers might deter the rooster. Plus, the case of one who slaughters a sacrifice on Shabbat or the holiday... How is one to treat the blood? Note that this discussion presumes that you have gone ahead with shichitah. Perhaps the mishnah could have been read differently.... Is the mishnah talking about a case of "after the fact," be-diavad, or an ideal lekhathilah situation? What needs to be done in advance to allow this to happen in the ideal fashion?