Mishnayos Chullin Perek 4 Mishnah 7

In the case of one who slaughters an animal and finds a placenta in its womb, one with a hearty soul [nefesh hayafa], i.e., who is not repulsed by it, may eat it, as its consumption was permitted by virtue of the slaughter of the mother. Nevertheless, since generally speaking, people do not consume such placentas, it is not regarded as food and so it cannot become impure with the ritual impurity of food even were it to come into contact with a source of impurity. And furthermore, it does not impart the ritual impurity of animal carcasses as it was permitted by virtue of the slaughter of the mother. But if one intended to eat it, one thereby elevated it to the status of food, and the placenta becomes impure with the ritual impurity of food if it comes into contact with a source of impurity. But even so, it still does not impart the ritual impurity of animal carcasses. With regard to a placenta, part of which emerged from the womb before the mother was slaughtered, its consumption is prohibited even after the mother animal is slaughtered because the emergence of the placenta is an indication of a fetus in a woman and an indication of a fetus in an animal. Accordingly, there is a concern that the head of the fetus might have emerged in that part of the placenta, thereby rendering the fetus as having been born, a status that precludes it from being permitted by the slaughter of its mother. Since the offspring is prohibited, its placenta is likewise prohibited. If an animal that was giving birth to its firstborn expelled a placenta, one may cast it to the dogs, and one does not need to be concerned that the placenta came from a male fetus that has the consecrated status of a firstborn. But in the case of sacrificial animals the placenta must be buried, because it came from a fetus that is assumed to have been sacred. The mishna adds: But one may neither bury it at an intersection, nor may one hang it on a tree, superstitious rites intended to prevent the animal from miscarrying again, due to the prohibition against following the ways of the Amorite, which prohibits Jews from practicing the superstitious rites observed by gentiles.

הַשּׁוֹחֵט אֶת הַבְּהֵמָה וּמָצָא בָהּ שִׁלְיָא, נֶפֶשׁ הַיָּפָה תֹּאכְלֶנָּה, וְאֵינָהּ מְטַמְּאָה לֹא טֻמְאַת אֳכָלִין וְלֹא טֻמְאַת נְבֵלוֹת. חִשֵּׁב עָלֶיהָ, מְטַמְּאָה טֻמְאַת אֳכָלִין אֲבָל לֹא טֻמְאַת נְבֵלוֹת. שִׁלְיָא שֶׁיָּצְתָה מִקְצָתָהּ, אֲסוּרָה בַאֲכִילָה. סִימַן וָלָד בָּאִשָּׁה, וְסִימַן וָלָד בַּבְּהֵמָה. הַמְבַכֶּרֶת שֶׁהִפִּילָה שִׁלְיָא, יַשְׁלִיכֶנָּה לִכְלָבִים. וּבַמֻּקְדָּשִׁין, תִּקָּבֵר. וְאֵין קוֹבְרִין אוֹתָהּ בְּפָרָשַׁת דְּרָכִים, וְאֵין תּוֹלִין אוֹתָהּ בְּאִילָן, מִפְנֵי דַּרְכֵי הָאֱמֹרִי: