יורה דעה פ״וYoreh De'ah 86

Se’if 1א׳

סִימָנֵי בֵּיצִים לְהַכִּיר שֶׁהֵם מֵעוֹף טָהוֹר; אִם שְׁנֵי רָאשֶׁיהָ כַּדִּין אוֹ חַדִּין, אוֹ שֶׁהָיָה חֶלְמוֹן מִבַּחוּץ וְחֶלְבּוֹן מִבִּפְנִים, בְּיָדוּעַ שֶׁהוּא בֵּיצַת עוֹף טָמֵא. וַאֲפִלּוּ אִם יֹאמַר הַמּוֹכֵר שֶׁהֵם מֵעוֹף טָהוֹר, אֵין סוֹמְכִין עָלָיו. וְאִם רֹאשׁוֹ אֶחָד כַּד וְעָגֹל וְרֹאשׁוֹ הַשֵּׁנִי חַד וְעָגֹל וְחֶלְבּוֹן מִבַּחוּץ וְחֶלְמוֹן מִבִּפְנִים, אֶפְשָׁר שֶׁהִיא בֵּיצַת עוֹף טָמֵא וְאֶפְשָׁר שֶׁהִיא בֵּיצַת עוֹף טָהוֹר. לְפִיכָךְ, שׁוֹאֵל לְצַיָּד יִשְׂרָאֵל, אוֹ עוֹבֵד כּוֹכָבִים, (טוּר וּבֵית יוֹסֵף בְּשֵׁם ה"ה שֶׁכֵּן כָּתַב בְּשֵׁם הריב"ח) הַמּוֹכֵר, אִם אָמַר לוֹ: שֶׁל עוֹף פְּלוֹנִי הוּא, וְאָנוּ מַכִּירִים שֶׁאוֹתוֹ עוֹף טָהוֹר הוּא, סוֹמֵךְ עָלָיו. וְאִם אָמַר: שֶׁל עוֹף טָהוֹר, וְלֹא אָמַר שְׁמוֹ, אֵינוֹ סוֹמֵךְ עָלָיו. לְפִיכָךְ אֵין לוֹקְחִין בֵּיצִים מִן הָעוֹבְדֵי כּוֹכָבִים, אֶלָּא אִם כֵּן הָיָה מַכִּיר אוֹתָם וְיֵשׁ לוֹ בָּהֶם טְבִיעוּת עַיִן שֶׁהֵם בֵּיצֵי עוֹף פְּלוֹנִי טָהוֹר; וְאֵין חוֹשְׁשִׁין לָהֶם שֶׁמָּא הֵם בֵּיצֵי טְרֵפָה אוֹ נְבֵלָה.

1. Identifying characteristics of eggs, and their laws. Containing 10 sections. Identifying characteristics of eggs, to recognize if they are from a "pure" bird species: If the two ends [of the egg] are both round, or pointed, or if the egg yolk is on the outside and the egg white on the inside, this is known to be the egg of an "impure" bird, and even if the seller says that they come from a "pure" bird, we do not rely on them. But if one end is convex and round, and the other end is pointed and round, and the egg white is on the outside and the egg yolk on the inside it is possible that it is the egg of an impure bird, but it is possible that it is the egg of a pure bird. Therefore, one must ask the Israelite (Or idolater) (citations) who is selling them. If they say, "It comes from such-and-such a bird," and we recognize that species of bird to be pure, one can rely on them. But if they say, "It comes from a pure bird," but cannot name the species of bird, one cannot rely on them. Therefore, one may not purchase eggs from the idolaters, unless one recognizes them, and they are visually identifiable to be the eggs of a pure bird. And we need not worry about the possibility that they might be eggs of a mortally ill [bird] or one who died of natural causes.

Se’if 2ב׳

עַכְשָׁו נוֹהֲגִים לִקַּח בֵּיצִים, בִּסְתָם, מִכָּל אָדָם, לְפִי שֶׁאֵין בֵּיצֵי עוֹף טָמֵא מָצוּי בֵּינֵינוּ. הַגָּה: וְדַוְקָא בַּבֵּיצִים הַשְּׁכִיחִים, דְּהַיְנוּ בֵּיצַת תַּרְנְגוֹלִים אוֹ אַוָּזוֹת וְכַיּוֹצֵא בָּהֶן, אֲבָל אֵין לוֹקְחִים בֵּיצִים מֵעוֹפוֹת שֶׁאֵינָם שְׁכִיחִים יוֹתֵר מֵעוֹפוֹת טְמֵאִים, עַד שֶׁיִּרְאֶה בַּסִּימָנִים, כְּמוֹ שֶׁנִּתְבָּאֵר. (אָרֹךְ כְּלָל מ"ב).

2. Currently the common practice is to purchase unmarked eggs from anyone, because eggs from impure birds are uncommon amongst us. RAMA: This is specifically about the ordinary type of eggs, that is, eggs of chickens or geese or similar ones to these. But one must not purchase eggs from birds that are not as common as those of impure birds, unless one observes the identifying characteristics, as will be explained. (Aruch, klal 42)

Se’if 3ג׳

בֵּיצַת נְבֵלָה וּטְרֵפָה, אֲפִלּוּ נִגְמְרָה, שֶׁכַּיּוֹצֵא בָּהּ נִמְכֶּרֶת בַּשּׁוּק, אֲסוּרָה. וַאֲפִלּוּ נִתְעָרְבָה בְּאֶלֶף, כֻּלָּן אֲסוּרוֹת. אֲבָל סָפֵק אִם הִיא בֵּיצַת נְבֵלָה אוֹ אִם הִיא בֵּיצַת שְׁחוּטָה, מֻתֶּרֶת, אֲפִלּוּ בְּלֹא תַּעֲרֹבֶת. אֲבָל סָפֵק אִם הִיא בֵּיצַת טְרֵפָה אוֹ בֵּיצַת שְׁחוּטָה, אֲסוּרָה. הַגָּה: וְאִם נִשְׁחֲטָה הַתַּרְנְגֹלֶת וְנִמְצֵאת טְרֵפָה, דִּין בֵּיצִים כְּדִין חָלָב שֶׁנֶּחְלַב מִבְּהֵמָה (בֵּית יוֹסֵף). וְעַיֵּן לְעֵיל סִימָן פ"א.

3. The egg of a mortally ill [bird] or one who died of natural (ie. non-slaughter) causes, even if it was so completely formed that similar ones are sold in the marketplace: it is prohibited. And even if it mixed with a thousand, they are all prohibited. But there is doubt whether the egg comes from one [bird] who died of natural causes, or by proper slaughter, it is permitted, even without being mixed [with permitted eggs]. But if there is doubt about whether it is the egg of a mortally ill [bird] or one who died by proper slaughter, it is prohibited. RAMA: And if the chicken was slaughtered and then found to be mortally ill, the rule for the eggs is like the rule for milk which was milked form an animal (B"Y) and see above section 81.