The Kashrut of Milk
כשרות החלב
Kosher (tahor) milk is milk from a kosher domesticated or wild animal, that is, from species of domesticated and wild animals whose meat is kosher for eating, such as a cow, a goat, and a deer. Non-kosher (tamei) milk is milk from a non-kosher domesticated or wild animal, whose meat is forbidden to eat, such as a donkey, a camel, a mare, and a sow. This is the rule: "That which comes from the impure is impure, and that which comes from the pure is pure" (Bekhorot 5b).¹
There are two differences between kosher and non-kosher milk: 1) Kosher milk can curdle into cheese, whereas non-kosher milk does not curdle. 2) The color of kosher milk is white, and that of non-kosher milk is yellowish (Avoda Zara 35b).
Even when the milk is from a kosher species, it may still be forbidden, for if it was milked from a tereifa animal, it is forbidden to eat. A tereifa is an animal that was injured in such a way that it will not live more than twelve months, or that has another defect that will cause its death within twelve months (above 20:2). Since death is eating away at its flesh, even if it is slaughtered in a kosher manner, its meat is forbidden to eat. And since its meat is forbidden to eat, its milk too is forbidden to eat. If a tereifa animal became mixed with kosher animals and was milked together with the rest of the animals, if the kosher animals were sixty times the tereifa, the milk of the tereifa is nullified in sixty and all the milk milked from the herd is kosher; if they were not sixty times as many, all the milk is forbidden (SA YD 81:1-2).
If a cow was milked and afterward slaughtered and found to be a tereifa, just as its meat is forbidden to eat, so too the milk milked from it is forbidden to eat, and the cheese made from it is also forbidden to eat. But if it is possible that the defect that rendered it tereifa developed after the milk from which the cheese was made was milked from it, the cheese is kosher, for as long as there is no proof that the animal was a tereifa at the time of milking, its milk retains a presumption (ḥazaka) of being kosher (ibid.).
If an animal was rendered tereifa because of a lung adhesion (sirkha), the milk milked from it in the three days close to its slaughter is forbidden. However, the milk milked from it before that is permitted because of a sfek sfeika (double doubt): perhaps the adhesion developed after the milk was milked, and perhaps this adhesion does not render it tereifa (Rema and SA YD 81:2; Zivḥei Tzedek 18; Kaf Ha-ḥayim 27).²
Notes (2)
- The Talmud asks (Bekhorot 6b) why it is permitted to drink milk. After all, only after the slaughter of a domesticated or wild animal may one eat its meat, whereas before that it is entirely forbidden, and anything separated from it is forbidden because of ever min ha-ḥai (a limb from a living animal) or basar min ha-ḥai (flesh from a living animal). Not only that, but milk is blood that has changed, become turbid, and turned into milk, and since blood is forbidden to eat, one might have thought that milk too is forbidden to eat. The Sages explained that since we learned in the Torah that the praise of the Land of Israel is that it is "a land flowing with milk and honey," it is clear that milk and honey are kosher to eat.
- Seemingly this is difficult: among dairy cows there are cows that are tereifot because of lung adhesions in the proportion of a mi’ut ha-matzui (a commonly found minority), and therefore by rabbinic law they must be checked after slaughter (above 20:4). So how is the milk of a cow permitted when it is known that a mi’ut ha-matzui of cows are tereifa? Rashi explained (Responsa 60) that the entire obligation to check for a mi’ut ha-matzui applies when it is possible to check, but when it is impossible to check, as with a cow before slaughter, one relies on the basic Torah law that we follow the majority. This was agreed upon by the Rishonim and Aḥaronim. Another important principle was explained by Mishkenot Ya’akov (YD 17): the rule that a living animal has a presumption of prohibition applies only to its meat, but regarding its milk, as long as we have not seen that the cow became tereifa, the milk by its nature has a presumption of permissibility (and similarly in Shibbolei Ha-leket 2:27). And although in practice after slaughter many cows are found to be tereifot, as long as they have not been slaughtered, the milk of each and every cow has a presumption of kashrut, since no indication of a problem (re’uta) has arisen regarding the cow from which it was milked.
However, one may still ask: sometimes most of the dairy cows are found to be tereifot, and if so we should be concerned about drinking the milk on the basis of the majority. This question was asked regarding the permission to slaughter on Yom Tov (above 20:8, n. 10): how is it permitted to slaughter in places and times where most animals are declared tereifot, so that most likely the slaughter is not for the purpose of eating, since it will be found to be a tereifa? The poskim answered that in truth, according to the basic law, a significant majority of animals are kosher, and only because of stringencies regarding adhesions do we declare many tereifa (Peri Ḥadash 39:3; Sha’agat Aryeh 64; Shiyurei Berakha 81:6; R. Akiva Eger; Arukh Ha-shulḥan 39:22). Thus, the permissibility of milk according to Rashi’s reasoning, which rests on the majority, remains in place. And according to the reasoning of Mishkenot Ya’akov, that the milk has a presumption of kashrut, even if it becomes clear after slaughter that most animals are tereifot by Torah law, the milk of each and every cow has a presumption of kashrut as long as it has not been proven to be a tereifa (Tiferet Tzvi YD 13).
A further question has arisen in recent generations: sometimes veterinarians need to operate on cows in places where, according to many, the incision renders them tereifa, and consequently their milk becomes non-kosher. Since generally they are not separated from the rest of the cows, if there are not sixty times as many kosher cows there, seemingly all the milk of the herd is forbidden to drink? Answer: First, some hold that any operation performed by a veterinarian for the cow’s health, after which it is known that it can live more than twelve months, does not render it tereifa, and so it appears in practice (above 20:3). Second, most operations are performed in places where there is a dispute whether an incision there renders it tereifa, such as a perforation of the rumen, and consequently it is a sfek sfeika (ibid.). In addition, there is no complete certainty that the milk brought from a particular barn is from a barn that has a cow that underwent an operation. And even if it is clear that there is a cow there that underwent an operation, perhaps its milk is nullified in sixty. And even if it is clear that there is not sixty times as much, it is milk of a doubtful tereifa, and the entire law of nullification in sixty for a mixture of the same kind (min be-mino) is rabbinic, and in a doubt the halakha follows the lenient (as written in Ḥokhmat Adam 37:6). Several Aḥaronim further wrote that if it is known that in the natural course these cows live twelve months after the operation, one may le-khatḥila nullify their milk in the milk of the majority of cows that were not operated on (Har Tzvi YD 36; Tzitz Eliezer 20:29; see Yabi’a Omer vol. 8, YD 2; unlike Responsa Maharsham 3:129, who was stringent). And although according to halakha and in practice animals that underwent operations are kosher (above 20:3), since many are stringent to consider them tereifot, in mehadrin kashrut one must take care not to mix in milk of cows that were operated on in places where there is a dispute whether this renders them tereifa.