Reference for Chullin 137:19

ק"ו אם הועיל לו סימן ראשון לסימן שני להתירו באכילה לא יועיל לו לטהריה מידי נבלה

if an animal that had been taken out [alive from the womb of the slaughtered dam] covered a normal cow there is no remedy for the offspring?<span class="x" onmousemove="('comment',' Because from the maternal side it requires to be slaughtered, but from the paternal side it does not; hence the offspring is considered, notionally, as half slaughtered, and nothing now can be done to it to remedy this state.');">¹¹</span>

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