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The Rambam’s view · Bekhorot 24 · בכורות כ״ד
Maternal Presumptions and Plucking Hair for Slaughter
How the Rambam rules on nursing presumptions regarding firstborn animals and the mechanics of clearing wool before slaughter.
Presumptions Established by Nursing
The Gemara discusses a person who purchases a nursing animal from a gentile. Under Torah law, a male firstborn must be consecrated to God. The Rabbis debate whether nursing proves that the mother has already given birth, or if a barren animal might nurse out of maternal instinct.
The Rambam rules firmly in accordance with Rabban Shimon ben Gamliel. An animal does not produce milk and nurse unless it has already given birth. Consequently, any subsequent offspring born to this mother is exempt from the sanctity of a בכור (firstborn animal).
לָקַח בְּהֵמָה מֵינִיקָה מִן הַנָּכְרִי אֵינוֹ חוֹשֵׁשׁ שֶׁמָּא בְּנָהּ שֶׁל אַחֶרֶת הִיא מֵינִיקָה אֶלָּא הֲרֵי זוֹ בְּחֶזְקַת שֶׁיָּלְדָה.When a person purchases an animal that is giving suck from a gentile, he need not suspect that it is giving suck to the offspring of another animal. Instead, we operate under the assumption that it has already given birth. (Mishneh Torah, Firstlings 4:8)
Nursing Across Species and Unresolved Doubts
The Gemara presents the inquiry of Rabbi Yoḥanan: what if a ewe is seen nursing an animal that resembles a pig? Since she nurses, she is exempt from future firstborn obligations even if the creature is of another species.
However, eating this pig-like creature presents an unresolved question. If an animal only nurses its own young, this creature was birthed by the kosher ewe and is permitted. If an animal might nurse across species lines, it may be the offspring of a real pig.
Because this inquiry ends in תיקו (an unresolved Talmudic dilemma), the Rambam rules that the creature is forbidden for consumption. The Maggid Mishneh explains that since this is an unresolved doubt in Torah law, we must rule stringently.
אֲבָל אִם הִנִּיחַ פָּרָה מְעֻבֶּרֶת בְּעֶדְרוֹ וּבָא וּמָצָא כְּמִין חֲזִיר כָּרוּךְ אַחֲרֶיהָ אַף עַל פִּי שֶׁהוּא יוֹנֵק מִמֶּנָּה הֲרֵי זֶה סָפֵק וְאָסוּר בַּאֲכִילָה.If, however, he left a pregnant cow in his herd and found an animal resembling a pig dependent on it, the matter is doubtful and it is forbidden to be eaten. (Mishneh Torah, Forbidden Foods 1:4)
Nursing Order in Flocks
The Gemara further explores a mixed flock where both first-time mothers and veteran mothers gave birth simultaneously without witnesses. In the morning, the shepherd finds males nursing from veteran mothers and females nursing from first-time mothers.
The Rambam rules that we do not suspect that the young swapped mothers. As Kiryat Sefer notes, a mother will not abandon her own young to nurse another in the presence of her offspring. The males are thus deemed definitively non-firstborn.
אֵינוֹ חוֹשֵׁשׁ שֶׁמָּא בְּנָהּ שֶׁל זוֹ בָּא לוֹ אֵצֶל זוֹ וּבְנָהּ שֶׁל זוֹ בָּא לוֹ אֵצֶל זוֹ אֶלָּא הֲרֵי הַדָּבָר בְּחֶזְקָתוֹ שֶׁכָּל אַחַת מֵינִיקָה בְּנָהּ:We do not suspect that the offspring of one went to another to suck and the offspring of the other went to the first. Instead, we follow the presumption that every animal is giving suck to its own offspring. (Mishneh Torah, Firstlings 5:4)
Plucking Wool for the Knife
The Mishnah records that Rabbi Yosei ben HaMeshullam permits clearing wool from the neck of a firstborn before slaughter. Although shearing consecrated animals is prohibited, one may pluck wool to make space for the knife.
The Rambam rules that this is permitted on condition that the plucked wool remains entangled in its place. He also permits plucking hair ab initio to show a blemish to an expert. Plucked hair remains forbidden from benefit so the owner will not delay slaughtering the animal to profit from its fleece.
הַשּׁוֹחֵט בְּכוֹר אוֹ שְׁאָר מֻקְדָּשִׁין. תּוֹלֵשׁ אֶת הַשֵּׂעָר מִכָּאן וּמִכָּאן לַעֲשׂוֹת מָקוֹם לַסַּכִּין. וּבִלְבַד שֶׁלֹּא יְזִיזֶנּוּ מִמְּקוֹמוֹ:When a person slaughters a firstborn or another consecrated animal, he may pull off the wool from either side to make a place for the knife, provided he does not remove the wool from its place. (Mishneh Torah, Trespass 1:11)
Applying the Leniency to Yom Tov
The Gemara applies this ruling to one who slaughters an ordinary animal on Yom Tov. The Rambam rules that one may pluck wool by hand on a festival to prepare a spot for the knife, as long as it remains tangled in place.
The Maggid Mishneh explains that plucking wool is fundamentally different from shearing: תולש לאו היינו גוזז (plucking is not considered shearing). Doing so by hand is an atypical deviation, known as כלאחר יד (backhanded or unusual manner), which is permitted for festival slaughter.
By contrast, plucking feathers from fowl on Yom Tov is strictly prohibited. Because plucking by hand is the standard method for fowl, it constitutes an act of forbidden shearing on the festival.
Nursing establishes past birth to exempt future offspring from firstborn sanctity, while hand-plucking animal wool is permitted before slaughter because plucking is not shearing.