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Incubator Chicks
‘These Are The Living Things You May Eat’
(Chullin 42a)



The following statement is found in Yad Chanoch (34): “Our friend, HaGaon Rabbi Shalom Mordechai HaKohen, has permitted the fowl hatched by the heat of an electric machine into which the eggs are put and because of the heat chicks hatch quickly and appear to be fully developed, but the trouble is that they cannot live more than 12 months and also cannot bear offspring.”

Many poskim who were asked about chicks hatched in an incubator agreed with this psak. Why would it not be permitted? Because Chazal state that an animal that cannot live more than 12 months is considered trefah.


What If It Naturally Dies Young?

Rabbi Meir Arik, zt”l (Imrei Yosher 1:145), explains that there’s no doubt that an animal that lives less than 12 months by nature is not trefah and offers an interesting proof. The Midrash says (cited in Eretz HaChayim, Tehillim 39:4) that a certain bird, a tzipor dror, lives 52 days. Nonetheless, it serves to purify a metzora. Now, we know that a trefah animal cannot purify a metzorah (Chulin 140a); the tzipor dror, therefore, must not be a trefah.

Chicks, however, generally live more than 12 months. If they live for less time than that because they’re born in an incubator, perhaps they should be considered trefah. Indeed, Rabbi Arik does consider them trefah (he bases his reasoning on Tosafos to Niddah 23a).

The Maharsham, however, disagrees (Responsa 3:378). He argues that an animal is only a trefah if it dies young due to a defect in its body. Chicks born in an incubator have no defect. It’s just that they are weak since incubation does not form chicks properly. They are considered weak animals, which have the status of a mesukenes – an endangered animal about to die – which, as our Gemara explains, is not trefah.


Incubator Eggs Are No Innovation

The Yad Chanoch, however, contends that these chicks are nevelah. At first, he asserts that raising chicks in an incubator is no innovation: “That which you thought, that it is something new recently invented, is not so. For even in the time of the Ramban, zt”l, who lived almost 1,000 years ago, people knew how to hatch chicks by heating the stove to a certain temperature. We thus see that people knew about this in former times.

“And in the land of Sini [China?], they would put the eggs in hot ashes at a certain temperature and produce chicks. And the voyager to the Orient, Rabbi Meshulam bar Rav Menachem of Valtira, zt”l, who traveled in 5241 [1581], recounted: ‘I saw Arabs growing fowl in stoves for they heat the stove and put therein the excrement of cattle and horses and put there 1,000 or 2,000 eggs, and chicks come out and they make fowl without end. Therefore, fowl is very cheap there.’”


People Used To Be Experts At Hatching Eggs

The obvious question, then, is why the Rishonim did not discuss these chicks? The Yad Chanoch explains that in former times “people were expert at this work and did it properly.” Therefore, the chicks were obviously permitted.

(He adds fascinating details in his reply: “And you should not wonder that they were better at this in former times. They knew how to do what is unknown in our time. Do not wonder, for Egyptian mummies and pyramids prove that recent generations, as much as they try, do not know how it is done. The same applies to the cup of herbal roots given to a woman that she should not become pregnant, which is unknown in our time.”

He continues: “And witness a wonder that an ill person on whom an operation had to be performed, Jewish doctors knew 2,000 years ago to give one a sleeping potion so that he would not feel pain, as explained in Bava Metzia 83b about Rabbi Elazar b. Rabbi Shimon, who was about to be operated on and was given a sleeping potion.

“And the same applies to someone who was punished with death; they would give him a sleeping potion to avoid the pain of death, as stated in Sanhedrin 43a. The gentile doctors knew nothing of this till about 200 years ago. Roman doctors would hit the patient’s head with a hammer before performing an operation to prevent the pain, but Jewish doctors knew 2,000 years to use a sleeping potion.”

At any rate, in his opinion, such chicks are nevelah as they are like a nefel (stillborn) that never developed properly and is forbidden by the Torah (see Imrei Yosher, ibid.).


Fowl Today

Virtually all the fowl we eat today are hatched in an incubator. But today, incubators are much more sophisticated, and there is no difference between chicks born in an incubator and chicks born naturally.


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Rabbi Yaakov Klass, rav of Congregation K’hal Bnei Matisyahu in Flatbush, Brooklyn, is Torah Editor of The Jewish Press. He can be contacted at