Shechita

In Judaism, shechita (anglicized: ; ; ; also transliterated "shehitah, shechitah, shehita") is slaughtering of certain mammals and birds for food according to "kashrut".
Biblical source.
The Torah () states that sheep and cattle should be slaughtered "as I have instructed you", but nowhere in the five books of Moses are any of the practices of "shechita" described. Instead, they have been handed down in Judaism's traditional Oral Torah, and codified in "halakha".
Species.
The animal must be of a permitted species. For mammals, this is restricted to ruminants which have split hooves. For birds, although biblically any species of bird not specifically excluded in would be permitted, doubts as to the identity and scope of the species on the biblical list led to
rabbinical law permitting only birds with a tradition of being permissible.
Fish do not require kosher slaughter to be considered kosher, but are subject to other laws found in which determine whether or not they are kosher (having both fins and scales).
"Shochet".
A "shochet" (, "slaughterer", plural "shochtim") is a person who performs "shechita". To become a "shochet", one must study which slaughtered animals are kosher, what disqualifies them from being kosher, and how to prepare animals according to the laws of "shechita". Subjects of study include the preparation of slaughtering tools, ways to interpret which foods follow the laws of "shechita", and types of "terefot" (deformities which make an animal non-kosher).
In the Talmudic era (beginning in 200 CE with the Jerusalem Talmud and 300 CE with the Babylonian Talmud and extending through the medieval ages), rabbis started to debate and define kosher laws. As the laws increased in number and complexity, following ritual slaughter laws became difficult for Jews who were not trained in those laws. 
This resulted in the need for a "shochet" (someone who has studied "shechita" extensively) to perform the slaughtering in the communities. "Shochtim" studied under rabbis to learn the laws of "shechita". Rabbis acted as the academics who, among themselves, debated how to apply laws from the Torah to the preparation of animals. 
Rabbis also conducted experiments to determine under which "terefot" animals were no longer kosher. "Shochtim" studied under these rabbis, as rabbis were the officials who first interpret, debate, and determine the laws of "shechita".
"Shochtim" are essential to every Jewish community, so they earn elevated social status. In medieval ages, the "shochtim" were treated as second in social status, just underneath rabbis. "Shochtim" were respected for committing their time to studying and for their importance to their communities.
An inspection (Heb. "bedikah") of the animal is required for it to be declared kosher, and a "shochet" has a double title: "Shochet u'bodek" (slaughterer and inspector), for which qualification considerable study as well as practical training is required.
Procedure.
The "shechita" procedure, which must be performed by a "shochet", is described in the relevant texts only as severing the wind pipe and food pipe (trachea and esophagus). Nothing is mentioned about veins or arteries. 
However, in practice, as a very long sharp knife is used, in cattle the soft tissues in the neck are sliced through without the knife touching the spinal cord, in the course of which four major blood vessels, two of which transport oxygenated blood to the brain (the carotid arteries) the other two transporting blood back to the heart (jugular veins) are severed. The vagus nerve is also cut in this operation. With fowl, the same procedure is followed, but a smaller knife is used.
A special knife is used, that is very long; and no undue pressure may be applied to the knife, which must be very sharp. The procedure may be performed with the animal either lying on its back (, "shechita munachat") or standing (, "shechita me'umedet"). 
In the case of fowl (with the exception of large fowl like turkey) the bird is held in the non-dominant hand in such a way that the head is pulled back and the neck exposed, while the cut made with the dominant hand.
The procedure is done with the intention of causing a rapid drop in blood pressure in the brain and loss of consciousness, to render the animal insensitive to pain and to exsanguinate in a prompt and precise action. 
It has been suggested that eliminating blood flow through the carotid arteries does not cut blood flow to the brain of a bovine because the brain is also supplied with blood by vertebral arteries, however other authorities note the distinction between severing the carotid versus merely blocking it.
If one did not sever the entirety of both the trachea and esophagus, then an animal may still be considered kosher as long as one severed the majority of the trachea and esophagus (windpipe and food pipe) of a mammal, or the majority of either one of these in the case of birds. The cut must be incised with a back-and-forth motion without employing any of the five major prohibited techniques (see below), or various other detailed rules.
Forbidden techniques.
Breaching any of these five rules renders the animal "nevelah"; the animal is regarded in Jewish law as if it were carrion.
Temple Grandin has observed that "if the rules (of the five forbidden techniques) are disobeyed, the animal will struggle. If these rules are obeyed, the animal has little reaction."
The knife.
The knife used for "shechita" is called a "sakin" (), or alternatively a "chalaf" () by Ashkenazi Jews. By biblical law the knife may be made from anything not attached directly or indirectly to the ground and capable of being sharpened and polished to the necessary level of sharpness and smoothness required for "shechita". The "minhag" now is to use a metal knife.
The knife must be at least slightly longer than the neck width but preferably at least twice as long as the animal's neck is wide, but not so long that the weight of the knife is deemed excessive. If the knife is too large, it is assumed to cause "derasah", excessive pressing. 
Kosher knife makers sell knives of differing sizes depending on the animal. Shorter blades may technically be used depending on the number of strokes employed to slaughter the animal, but the normative practice today is that shorter blades are not used. 
The knife must not have a point. It is feared a point may slip into the wound during slaughter and cause "haladah", covering, of the blade. The blade may also not be serrated, as serrations cause "iqqur," tearing.
The blade cannot have imperfections in it. All blades are assumed by Jewish law to be imperfect, so the knife must be checked before each session. In the past the knife was checked through a variety of means. Today the common practice is for the "shochet" to run his fingernail up and down both sides of the blade and on the cutting edge to determine if he can feel any imperfections. He then uses a number of increasingly fine abrasive stones to sharpen and polish the blade until it is perfectly sharp and smooth. 
After the slaughter, the "shochet" must check the knife again in the same way to be certain the first inspection was properly done, and to ensure the blade was not damaged during "shechita". If the blade is found to be damaged, the meat may not be eaten by Jews. If the blade falls or is lost before the second check is done, the first inspection is relied on and the meat is permitted.
In previous centuries, the "hallaf" was made of forged steel, which was not reflective and was difficult to make both smooth and sharp. Shneur Zalman of Liadi, fearing that Sabbateans were scratching the knives in a way not detectable by normal people, introduced the Hasidic "hallaf" (). 
It differs from the previously-used knife design because it is made of molten steel and polished to a mirror gloss in which scratches could be seen as well as felt. The new knife was controversial and one of the reasons for the 1772 excommunication of the Hasidim. As of present time, the "Hassidic hallef" is now universally accepted and is the only permitted blade allowed in religious communities. 
Other rules.
The animal may not be stunned prior to the procedure, as is common practice in non-kosher modern animal slaughter since the early 20th century.
It is forbidden to slaughter an animal and its young on the same day. An animal's "young" is defined as either its own offspring, or another animal that follows it around, even if of another species.
The animal's blood may not be collected in a bowl, a pit, or a body of water, as these resemble ancient forms of idol worship.
If the "shochet" accidentally slaughters with a knife dedicated to idol worship, he must remove an amount of meat equivalent to the value of the knife and destroy it. If he slaughtered with such a knife on purpose, the animal is forbidden as not kosher.
Post-procedure requirements.
Bedikah.
The carcass must be checked to see if the animal had any of a specific list of internal injuries that would have rendered the animal a "treifah" before the slaughter. These injuries were established by the Talmudic rabbis as being likely to cause the animal to die within 12 months time. 
Today all mammals are inspected for lung adhesions ( "examination of the lung") and other disqualifying signs of the lungs, and most kosher birds will have their intestines inspected for infections. 
Further inspection of other parts of the body may be performed depending on the stringency applied and also depending on whether any signs of sickness were detected before slaughter or during the processing of the animal.
Glatt.
"Glatt" () and "halak" () both mean "smooth". In the context of kosher meat, they refer to the "smoothness" (lack of blemish) in the internal organs of the animal. In the case of an adhesion on cattle's lungs specifically, there is debate between Ashkenazic customs and Sephardic customs. While there are certain areas of the lung where an adhesion is allowed, the debate revolves around adhesions which do not occur in these areas.
Ashkenazic Jews rule that if the adhesion can be removed (there are various methods of removing the adhesion, and not all of them are acceptable even according to the Ashkenazic custom) and the lungs are still airtight (a process that is tested by filling the lungs with air and then submerging them in water and looking for escaping air), then the animal is still kosher but not "glatt". 
If, in addition, there were two or fewer adhesions, and they were small and easily removable, then these adhesions are considered a lesser type of adhesion, and the animal is considered "glatt". Ashkenazi custom permits eating non-"glatt kosher" meat, but it is often considered praiseworthy to only eat "glatt kosher" meat.
Sephardic Jews rule that if there is any sort of adhesion on the forbidden areas of the lungs, then the animal is not kosher. This standard is commonly known as "halak Beit Yosef". It is the strictest in terms of which adhesions are allowed. 
However, despite this ruling, in practice most Sephardic and Mizrahi communities historically ate non-"halak" meat, except those in Syria, Egypt, Iraq, and the Land of Israel.
The Rema (an Ashkenazi authority) had an additional stringency, of checking adhesions on additional parts of the lung which Sephardi practice does not require. Some Ashkenazi Jews keep this stringency.
Nikkur.
"Porging" refers to the "halakhic" requirement to remove the carcass's veins, "chelev" (caul fat and suet) and sinews. The Torah prohibits the eating of certain fats, so they must be removed from the animal. These fats are typically known as "chelev". There is also a biblical prohibition against eating the sciatic nerve ("gid hanasheh"), so that, too, is removed.
The removal of the "chelev" and the "gid hanasheh", called "nikkur", is considered complicated and tedious, and hence labor-intensive, and even more specialized training is necessary to perform the act properly. 
While the small amounts of "chelev" in the front half of the animal are relatively easy to remove, the back half of the animal is far more complicated, and it is where the sciatic nerve is located.
In countries such as the United States, where there exists a large non-kosher meat market, the hindquarters of the animal (where many of these forbidden meats are located) is often sold to non-Jews, rather than trouble with the process. 
This tradition goes back for centuries where local Muslims accept meat slaughtered by Jews as consumable; however, the custom was not universal throughout the Muslim world, and some Muslims (particularly on the Indian subcontinent) did not accept these hindquarters as "halal". In Israel, on the other hand, specially trained men are hired to prepare the hindquarters for sale as kosher.
Kashering.
Because of the biblical prohibition of eating blood, all blood must be promptly removed from the carcass. 
All large arteries and veins are removed, as well as any bruised meat or coagulated blood. Then the meat is "kashered", a process of soaking and salting the meat to draw out all the blood. 
If this procedure is not performed promptly, the blood is considered to have "set" in the meat, and the meat is no longer salvageable to eat except when prepared through broiling with appropriate drainage.
Giving of the Gifts.
The Torah requires a "shochet" to give the foreleg, cheeks and maw to a "kohen" even though he does not own the meat. Thus, it is desirable that the "shochet" refuse to perform the "shechita" unless the animal's owner expresses his agreement to give the gifts. Rabbinical courts have the authority to excommunicate a "shochet" who refuses to perform this commandment.
The "Rishonim" pointed out that the "shochet" cannot claim that, since the animal does not belong to him, he cannot give the gifts without the owner's consent. On the contrary, since the average "shochet" is reputed to be well versed and knowledgeable in the laws of "shechitah" ("Dinnei Shechita"), the rabbinical court relies on him to withhold his "shechita" so long as the owner refuses to give the gifts.
Covering of the blood.
It is a positive commandment incumbent upon the "shochet" to cover the blood of חיות (non-domesticated animals) and עופות (birds) but not בהמות (domesticated animals). 
The "shochet" is required to place dirt on the ground before the slaughter, and then to perform the cut over that dirt, in order to drop some of the blood on to the prepared dirt. When the "shechita" is complete, the "shochet" grabs a handful of dirt, says a blessing and then covers the blood. 
The meat is still kosher if the blood does not get covered; covering the blood is a separate mitzvah which does not affect the kosher status of the meat.
Animal welfare controversies.
"Opposition to the Jewish methods of slaughter has a long history, starting at least as far back as the mid-Victoria era."
The Gutachten (expert reports).
When "shechita" came under attack in the 19th century, Jewish communities resorted to expert scientific opinions which were published in pamphlets called " Gutachten". Among these authorities was Joseph Lister, who introduced the concept of sterility in surgery.
General description of controversy.
The practices of handling, restraining, and unstunned slaughter have been criticized by, among others, animal welfare organizations such as Compassion in World Farming. The UK Farm Animal Welfare Council said that the method by which kosher and "halal" meat is produced causes "significant pain and distress" to animals and should be banned. 
According to FAWC it can take up to two minutes after the incision for cattle to become insensible. Compassion in World Farming also supported the recommendation saying "We believe that the law must be changed to require all animals to be stunned before slaughter."
The recommendations which the Government have accepted will lead to significant improvements in animal welfare. 
Mr Bradshaw said the Government had maintained its position in not accepting FAWC's recommendation that slaughter without prior stunning should be banned, as they respected the rights of communities in Britain to slaughter animals in accordance with the requirements of their religion.
The Federation of Veterinarians of Europe has issued a position paper on slaughter without prior stunning, calling it "unacceptable." 
The American Veterinary Medical Association has no such qualms, as leading US meat scientists support "shechita" as a humane slaughtering method as defined by the Humane Slaughter Act.
A 1978 study at the University of Veterinary Medicine Hanover indicates that "shechita" gave results which proved "...pain and suffering to the extent as has since long been generally associated in public with this kind of slaughter cannot be registered..." and that "[a complete loss of consciousness] occurred generally within considerably less time than during the slaughter method after captive bolt stunning.". However, the lead of the study William Schulze warned in his report that the results may have been due to the captive bolt device they used being defective.
Nick Cohen, writing for the "New Statesman", discusses research papers collected by Compassion in World Farming which indicate that the animal suffers pain during the process. In 2009, Craig Johnson and colleagues showed that calves that have not been stunned feel pain from the cut in their necks, and they may take at least 10–30 seconds to lose consciousness.
Temple Grandin says that the experiment needs to be repeated using a qualified "shochet" and knives of the correct size sharpened in the proper way.
Jewish and Muslim commentators cite studies that show "shechita" is humane and that criticism is at least partially motivated by antisemitism. A Knesset committee announced (January, 2012) that it would call on European parliaments and the European Union to put a stop to attempts to outlaw kosher slaughter.
"The pretext [for this legislation] is preventing cruelty to animals or animal rights—but there is sometimes an element of anti-Semitism and there is a hidden message that Jews are cruel to animals," said Committee Chair MK Danny Danon (Likud).
Studies done in 1994 by Dr. Temple Grandin, an Associate Professor of Animal Science at Colorado, and another in 1992 by Dr. Flemming Bager, Head of the Danish Veterinary Laboratory, showed that when the animals were slaughtered in a comfortable position they appeared to give no resistance and none of the animals attempted to pull away their head. The studies concluded that a shechita cut "probably results in minimal discomfort" because the cattle stand still and do not resist a comfortable head restraint device.
Temple Grandin—a leading designer of animal handling systems—gives various times for loss of consciousness via kosher ritual slaughter, ranging from 15 to 90 seconds depending on measurement type and individual kosher slaugtherhouse. She elaborates on what parts of the process she finds may or may not be cause for concern. In 2018, Grandin stated that kosher slaughter, no matter how well its done, is not instantaneous, whereas stunning properly with a captive bolt is instantaneous.
Efforts to improve conditions in "shechita" slaughterhouses.
Temple Grandin is opposed to shackling and hoisting as a method of handling animals and wrote, on visiting a "shechita" slaughterhouse,
Efforts are made to improve the techniques used in slaughterhouses. Temple Grandin has worked closely with Jewish slaughterers to design handling systems for cattle, and has said: "When the cut is done correctly, the animal appears not to feel it. From an animal-welfare standpoint, the major concern during ritual slaughter are the stressful and cruel methods of restraint (holding) that are used in some plants." 
When shackling and hoisting is used, it is recommended that cattle not be hoisted clear of the floor until they have had time to bleed out.
Agriprocessors controversy.
The prohibition of stunning and the treatment of the slaughtered animal expressed in "shechita" law limit the extent to which Jewish slaughterhouses can industrialize their procedures. 
The most industrialized attempt at a kosher slaughterhouse, Agriprocessors of Postville, Iowa, became the center of controversy in 2004, after People for the Ethical Treatment of Animals released a gruesome undercover video of cattle struggling to their feet with their tracheas and esophagi ripped out after "shechita". Some of the cattle actually got up and stood for a minute or so after being dumped from the rotating pen. 
While Agriprocessors has been criticized by both secular and Jewish organizations for both its human and animal rights violations, the Orthodox Union (OU) made note to point out that the "kashrut" of a product is not contingent upon "the conditions in which it is produced. 
The OU's condonation of Agriprocessors as a possibly inhumane, yet appropriately "glatt" kosher company has led to discussion as to whether or not industrialized agriculture has undermined the place of "halakha" (Jewish law) in "shechita" as well as whether or not "halakha" has any place at all in Jewish ritual slaughter.
Jonathan Safran Foer, a Jewish vegetarian, narrated the short documentary film "If This Is Kosher...", which records what he considers abuses within the kosher meat industry. 
Forums surrounding the ethical treatment of workers and animals in kosher slaughterhouses have inspired a revival of the small-scale, kosher-certified farms and slaughterhouses, which are gradually appearing throughout the United States.