11הַבְּכוֹר שֶׁנֶּאֱכַל בְּשָׂרוֹ כַּהֲלָכָה בֵּין תָּמִים בֵּין בַּעַל מוּם. כְּשֵׁם שֶׁמֻּתָּר לֵהָנוֹת בְּעוֹרוֹ כָּךְ נֶהֱנִין בְּגִזּוֹתָיו. אֲבָל כָּל צֶמֶר שֶׁנִּגְזַז מִמֶּנּוּ כְּשֶׁהוּא חַי אֲפִלּוּ נָשַׁר הֲרֵי הוּא אָסוּר בַּהֲנָאָה. וַאֲפִלּוּ נָשַׁר מִמֶּנּוּ אַחַר שֶׁנָּפַל בּוֹ מוּם. וַאֲפִלּוּ אַחַר שְׁחִיטָתוֹ וְאֵין צָרִיךְ לוֹמַר אַחַר מִיתָתוֹ שֶׁהֲרֵי אוֹתוֹ הַצֶּמֶר שֶׁנָּשַׁר מִמֶּנּוּ מֵחַיִּים בְּאִסּוּרוֹ עוֹמֵד. וְכֵן בְּמַעֲשַׂר בְּהֵמָה. וּכְבָר בֵּאַרְנוּ בְּהִלְכוֹת מְעִילָה שֶׁלֹּא גָּזְרוּ גְּזֵרָה זוֹ אֶלָּא עַל הַבְּכוֹר וְעַל הַמַּעֲשֵׂר בִּלְבַד מִפְּנֵי שֶׁאֵינָן בָּאִין לְכַפָּרָה שֶׁמָּא יַשְׁהֵם אֶצְלוֹ כְּדֵי לִקַּח כָּל הַצֶּמֶר שֶׁיִּנְשֹׁר מֵהֶם. וּכְבָר בֵּאַרְנוּ שֶׁמִּצְוָה לְאָכְלוֹ תּוֹךְ שְׁנָתוֹ בֵּין תָּמִים בֵּין בַּעַל מוּם:
When the meat of a firstborn animal, whether unblemished or blemished, has been eaten according to law, just as it is permitted to benefit from its hide, so too, is it permitted to benefit from its shearings. Nevertheless, it is forbidden to benefit from any wool which is cut off from it while it is alive - and even from wool that it shed, and even to wool that was shed after the animal contracted a blemish. Even after it was slaughtered, and, needless to say, after it died, the wool remains forbidden. For the same wool that was shed from the animal during its lifetime remains forbidden even after these events take place. These same laws apply with regard to the tithes of animals. We have already explained in Hilchot Me'ilah that this decree was instituted only with regard to the firstborn and tithe sacrifices, because they do not come to secure atonement. Hence with regard to these sacrifices, there is room to suspect that the owner will leave them in his domain to take all the wool that sheds from them. This is undesirable, because as we have already explained, it is a mitzvah to eat the firstborn in the first year of its life, whether it is unblemished or blemished.