What Milk is Kosher?
1) In regard to the subject of kosher milk, the general principle is that whatever issues from the impure is itself impure. This is to say that only the milk of kosher animals is kosher. Of domesticated animals, this includes the milk of cows, sheep and goats. Of undomesticated animals, this includes the milk of the addax, antelope, bison, buffalo, deer, gazelle, ibex and reindeer, as well as many other animals too numerous to enumerate here.
Cholov Akum – Non-Jewish Milk
2) Even though, today, in such countries as the U.S.A., Canada, and the United Kingdom etc., it is not common practice amongst non-Jews to consume anything other than the milk of cows, sheep and goats, nonetheless, in many cultures the consumption of milk from non-kosher animals is common. To give just two examples; in Arab cultures, it is common to consume camel milk and in Mexico it is common to consume donkey milk, which is thought to be highly nutritional and healthy. Out of concern that milk purchased from non-Jews may contain a mixture of non-kosher milk, our holy sages forbade the consumption of any milk product that has not been supervised by a Jew from the time of milking. This is to assure that the milk is wholly the product of kosher animals, such as cows, sheep or goats.
Cholov Yisroel – Supervised Milk
3) Even if there are only cows, sheep and goats on the non-Jewish dairy farm, the milk may not be consumed if it was not supervised from the time of milking. Since non-kosher milk could be brought from elsewhere, supervision still is needed to assure against this. Furthermore, it makes no difference whether the milk was produced for personal use, to be sold on the open market or specifically for Jewish consumption. Even if the proprietor agrees contractually to provide 100% pure cow milk and there are only kosher animals on his farm, the milking must still be supervised.
4) Moreover, according to some authorities, even in an area where there are no non-kosher animals or where the non-Jews would never milk non-kosher animals because such milk is disgusting to them or where there is no financial gain in committing fraud because the milk of non-kosher animals is more expensive than the milk of kosher animals, nevertheless, the milking must still be supervised. This is because a rabbinical decree that has become universally accepted and firmly established through long-standing practice may not be abrogated by rabbis of later generations, unless they are greater than the rabbis of the previous generations. This is the case even if the original reason for the decree is no longer applicable.
According to this opinion there are two categories of milk;
a) Milk that was supervised from the time of milking. This is considered to be cholov Yisroel-Jewish milk, and may be consumed.
b) Milk that was not supervised from the time of milking. This is considered to be cholov Akum – Non-Jewish milk, and may not be consumed.
Cholov Stam – Plain Milk
5) However, there are Halachic authorities that state that the decree was only meant to apply to a situation in which there is some reason to suspect the possibility of mixture. Therefore, in a case where the possibility is practically nonexistent, such as in a country that has strict governmental controls against it, including the threat of heavy fines, law suites, suspension of operations and even closure etc., many modern authorities permit the consumption of unsupervised milk, especially if it is difficult to obtain supervised milk.
Accordingly, in practical terms, there are three categories of milk:
A) Cholov Yisroel – Jewish milk. This is milk which was supervised from the time of milking. This milk may be consumed.
B) Cholov Akum – non-Jewish milk. This is unsupervised milk which was produced in a country that does not have heavy governmental restrictions and enforcement prohibiting the admixture of milk. This milk may not be consumed.
C) Cholov Stam – Plain milk. This is unsupervised milk which was produced in a country that has heavy governmental regulations prohibiting the admixture of milk and which strictly enforces them. This assures the absence of admixture. This milk may be consumed and is treated as if it actually was supervised. According to this opinion, such milk is basically on the same level as supervised cholov Yisroel milk.
5) However, though this practice has become widely accepted, it is by no means universal. There are many who only consume cholov Yisroel milk products that have been supervised from the actual milking process. However they may do so for diverse reasons:
A1) Because they adhere to the first opinion, stated above, that only supervised milk may be consumed and that all other milk is forbidden, even in a country that has heavy regulations which are strictly enforced.
A2) In addition, because this opinion considers unsupervised milk to be non-kosher even in a country that has heavy regulations, therefore, the consumption of such milk causes intellectual and emotional insensitivity to spirituality as does the consumption of any forbidden food.
B) They agree with the second opinion, that milk produced in a country that has strict regulations which are enforced, need not be supervised. However, as a personal stricture, they take it upon themselves to be extra careful to consume only cholov Yisroel products. They do this as an additional act of piety of going beyond the letter of the law.
6) The practical outcome of these two approachesis as follows:
a) Those people who consume cholov Yisroel as a Halachic obligationwill consider any pots, utensils or plates that have been used with hot unsupervised milk products to be non-kosher. Therefore, they will not eat from such vessels.
b) However, those people who consume cholov Yisroel as a matter of personal piety will consider pots, utensils and plates that have been used with hot unsupervised milk to be kosher. Therefore, they will eat from such vessels.
c) In addition, in the case of a family that goes from eating cholov stam to keeping strictly cholov Yisroel, rabbis that regard cholov Yisroel as a Halachic obligation will require them to re-kosher or replace their dairy utensils, whereas rabbis that allow cholov stam will not.
7) An additional outcome of the two approaches is as follows:
a) Since they regard it to be a Halachic obligation, the first group will make sure that all the members of their household will also eat only cholov Yisroel and will not bring cholov stam into their house.
b) Since they regard it as a voluntary act of piety, rather than a Halachic obligation, the second group will not impose it upon the other members of their household and will allow cholov stam to be brought into the house.
Inquire of your rabbi as to how you should conduct yourself in all the above.
8) It must be pointed out that packaged dairy products which bear a kosher symbol are generally not cholov Yisroel-not supervised from the milking (unless indicated by the additional words cholov Yisroel-(חלב ישראל. These products will usually display the kosher symbol with the letter D next to it.
9) It should also be pointed out that packages that bear a kosher symbol with the letters DE next to it are products that were made with ingredients which are neither milk nor meat. However, they were made on non-cholov Yisroel dairy equipment. This being the case, people who consume cholov Yisroel as a Halachic obligation will consider these products to be non-kosher. On the other hand, people who consume cholov stam or who consume cholov Yisroel as a matter of personal piety will consider them to be kosher and pareve (neither milk nor meat).
10) Though some authorities do not require supervision for plain milk produced in a country that has strict governmental controls against admixture, nonetheless, all are in agreement that the production of processed dairy foods, such as cheeses, sour creams, yogurts, ice-creams etc., need supervision to assure that only kosher equipment and ingredients are used and that no mixture of milk and meat takes place.
 רמב”ם מאכלות אסורות ג:א.
 שו”ע יו”ד פא:א.
 רמב”ם מאכלות אסורות א:ח.
 רמב”ם שם.
 גמ’ ע”ז לה:ב, רמב”ם מאכלות אסורות ג:טו, שו”ע יו”ד קטו:א.
 ט”ז יו”ד קטו:ב, דרכ”ת יו”ד קטו:ו, כה”ח יו”ד קטו:טו.
 ט”ז יו”ד קטו:א, ש”ך יו”ד קטו:א.
 רמב”ם ממרים ב:ב- ב:ג, ערוה”ש יו”ד קטו:ה, חכמ”א סז:א.
 שו”ת הרדב”ז ד:עה.
 אג”מ יו”ד א:מז-מט, חזו”א יו”ד מא:ד.
 אג”מ שם.
 מכלל שטמטום המוח והלב בא מאכילת כל דבר איסור. גמ’ שבת קמה:ב – מפני מה עכו”ם מזוהמים מפני שאוכלין שקצים ורמשים, וראה רמ”א יו”ד פא:ז וש”ך וט”ז שם. וקובץ בית הלל שנה א-גליון ב, עמ’ מז מבאר הענין בארוכה. ראה אבן עזרא, מלבי”ם ותורה תמימה על ויקרא יא:מג, וגם ראה ספר אילנא דחיי עמ’ לג וספר המאמרים תשי”א עמ’ ו.
 אבל לדעה שחלב סתם הוא חלב ישראל לדינא, אין חשש כלל שיטמטם המוח והלב. ראה אג”מ יו”ד א:מו-מז-מח-מט, אג”מ יו”ד ב:לא-לה-מז-מח, אג”מ יו”ד ג:טז, אג”מ יו”ד ד:ה.