Cloned Pigs Aren’t Kosher

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by R. Gil Student

I. Kosher Pig

The news recently carried a report that Rav Yuval Cherlow said that cloned pigs are kosher. This is clearly wrong. A cloned pig is implanted as an embryo into a female pig and born naturally. There is no reason it should not be treated halakhically like other pigs, indeed like its clone.

Presumably, Rav Cherlow meant lab-grown meat from a pig stem cell. However, even this poses challenges. The issue has been discussed in journals and the consensus forbids lab-grown pig meat for a number of reasons. This is a complex question and in my limited space here I will give just a brief overview of only some of the issues.

To the best of my knowledge, Rav J. David Bleich published the first article on the subject in Tradition 46:4 (Winter 2013), arguing that it is forbidden. Rav Tzvi Ryzman argued that it would be permitted, in the Israeli journal Techumin (no. 34, 2014). Rav Ya’akov Ariel included a brief rebuttal in that issue, which was expanded to a full article in issue no. 36. In the meantime, Rav Yehuda Spitz published his own rebuttal in issue no. 35. Rav Spitz also published an English article on the subject in The Journal of Halacha and Contemporary Society (no. 72, Fall 2016). An article was just published in the latest issue of Hakirah (vol. 24, Spring 2018), but I had not yet seen it at the time of writing this essay.

II. Microscopic Pig

One argument in favor is that the pig stem cells is microscopic. Since the Torah does not forbid anything that is invisible to the naked eye, the cell itself is permissible. Therefore, any meat that grows from it must be permissible, as well.

Both Rav J. David Bleich and Rav Ya’akov Ariel point out that in this case we do not discount the microscopic cell because we manipulate it. It comes from a large animal and will grow into a visible item, and in between humans interact with it. He compares this case to that discussed in Rav Shlomo Zalman Auerbach’s responsum regarding the grafting of cells from different species of vegetation (Minchas Shlomo, Tinyana, no. 100).

Rav Auerbach prohibited this grafting of particles as a forbidden mixture (kilayim) even though it is done completely on a microscopic basis. Since people are interacting with them, those particles cannot be considered insubstantial and halakhically irrelevant. Similarly, Rav Ariel argues, the pig cell is manipulated and used for meat growth. Therefore, it cannot be considered insubstantial.

III. New Item

Rav Ryzman compares the cell growth process to the production of gelatin. In the production of gelatin, an animal’s skin and bones are rendered inedible, thereby removing their prohibition according to some authorities. Similarly, Rav Ryzman argues, the pig cell is inedible and should lose its prohibition.

Rav Ariel counters that the cases are different. The skin and bones are rendered inedible. The pig cell is inedible only because of its small size — really, it remains edible throughout the process. Therefore, even the authorities that permit gelatin would not permit lab-grown pig meat.

IV. Dilution

As a general rule, a prohibited item is diluted in a mixture in which it is either a simple minority or less than one-sixtieth, depending on the circumstance. When a pig cell is added to growth medium, the cell is diluted in much more than one-sixtieth. Therefore, it should be permitted.

Rav Bleich argues that the pig cell is considered a davar ha-ma’amid, a substance that supports or upholds the mixture. A davar ha-ma’amid is not diluted in any amount. The original pig stem cell serves to support the meat that grows — it is the catalyst for the entire process. Therefore, the pig cell is not diluted and nullified but remains with its original prohibition.

Rav Ariel adds that there is no actual mixture. The pig stem cell is placed in a growth medium and then grow. The result is many more pig cells that grow from the original stem cell. Rather than a mixture, this is just one substance growing substantially. The lab-grown meat consists of the original stem cell multiplied greatly, containing the forbidden status of the original cell.

V. Live Cell

The original pig cell is taken from a live animal. Currently, there is no way to take viable cells from a dead animal. In addition to the prohibition of pig, the cell also has the prohibition of meat or a limb from a live animal (eiver min ha-chai). Eiver min ha-chai is one of the Noahide commandments that bind all of humanity. Therefore, not only are Jews forbidden to eat lab-grown meat, even gentiles may not eat it.

The media seems to have enjoyed the paradoxical discussion about kosher pig meat. However, the consensus seems to be that this lab-grown pig meat is forbidden for multiple reasons. According to Rav Ariel, it is even less kosher than natural pig meat because even gentiles cannot eat this lab-grown meat.

About Gil Student

Rabbi Gil Student is the Publisher and Editor-in-Chief of, a leading website on Orthodox Jewish scholarly subjects, and the Book Editor of the Orthodox Union’s Jewish Action magazine. He writes a popular column on issues of Jewish law and thought featured in newspapers and magazines, including The Jewish Link, The Jewish Echo and The Vues. In the past, he has served as the President of the small Jewish publisher Yashar Books and as the Managing Editor of OU Press. Rabbi Student serves on the Executive Committee of the Rabbinical Council of America. He also serves on the Editorial Boards of Jewish Action magazine, the Journal of Halacha and Contemporary Society and the Achieve Journal of Behavioral Health, Religion & Community, as well as the Board of OU Press. He has published five English books, the most recent titled Search Engine volume 2: Finding Meaning in Jewish Texts -- Jewish Leadership, and served as the American editor for Morasha Kehillat Yaakov: Essays in Honour of Chief Rabbi Lord Jonathan Sacks.


  1. Joel Kenigsberg

    You wrote “Currently, there is no way to take viable cells from a dead animal”. I believe this is inaccurate. It’s true that the research to date has been conducted on cells from live animals but the technology does exist to take cells from an animal that has already been slaughtered. (This was confirmed to me by Mark Post, creator of the world’s first labgrown hamburger). Starter cells from a kosher, slaughtered animal would presumably be the best solution, according to all authorities.

    Another point to take into account is the nature of the growth medium. To date, nearly all growth mediums contain fetal bovine serum, derived from blood of unborn cows. Thus the mixture argument becomes redundant. However, the future technology is touted to be serum free – due to issues of sustainability, health and cost.

  2. If ever min ha chai is the issue, then the same problem would be present for cloned beef, chicken or lamb. (If as per Joel’s comment, one could used shechted meat, then that would not be an issue.)

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