Midrash su Deuteronomio 14:6

1) "All … in the beast (may you eat"): to include (as permitted) the fetus (found "in the beast" after its mother had been slaughtered). I might think (that this were so) even if part of it had emerged. It is, therefore, (to negate this,) written "Only (this may you not eat.") "it (one with the signs of cleanliness) may you eat." It may be eaten (and not an unclean beast.)

9) (Devarim 14:6): "And every beast that has split hooves, entirely cloven in two, and which chews the cud in the beast — it may you eat" — to include the embryo (as permitted with the slaughtering of the mother). If the fetus stuck out its hand and returned it, it (the fetus, excluding the hand) may be eaten (with the slaughtering of its mother.) I might think that even if it stuck out its head and returned it, it is permitted with the slaughtering of its mother; it is, therefore, (to negate this) written (Devarim 14:7): "Only (this may you not eat") Why do you see fit to say that if the fetus stuck out its hand and returned it, it (the fetus) may be eaten (with the slaughtering of its mother)? Because it is not considered to have been born (and to require its own slaughtering). And why do you see fit to say that if the fetus stuck out its head, it (the fetus) may not be eaten (with the slaughtering if its mother)? Because it is considered to have been born (and to require its own slaughtering).

(Devarim 14:6) "And every beast that has split hooves": Because we find that Scripture construed "treifah" ("torn" [in Shemoth 22:30 "and flesh in the field treifah you shall not eat"]) as "treifoth" (i.e., varieties of treifah that are forbidden to all [even non-priests]), I will also construe "pasul" (unfit) as "p'sulim" (i.e., unfit for eating for all), e.g., one's plowing with an ox and an ass (together), or with (animals dedicated as) offerings. It is, therefore, written (to include these as permitted to be eaten) "the ox, the lamb of sheep, and the kid of goats shall you eat."