, 1940 The
shechita procedure, which must be performed by a
shochet, is described in the
Yoreh De'ah section of the
Shulchan Aruch 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 of considerable length is used; 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. 's collection. 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, but other authorities note the distinction between severing the carotid versus merely blocking it. or various other detailed rules.
Forbidden techniques •
Shehiyah (; delay or pausing)Pausing during the incision and then starting to cut again makes the animal's flesh unkosher. The knife must be moved across the neck in an uninterrupted motion until the trachea and esophagus are sufficiently severed to avoid this. There are those who assert that it is forbidden to have the animal in an upright position during
shechita due to the prohibition of
derasah. They maintain that the animal must be on its back or lying on its side, and some also allow for the animal to be suspended upside down. However, the Rambam explicitly permits upright slaughter, •
Haladah (; covering, digging, or burying)The knife must be drawn over the throat so that the back of the knife is at all times visible while
shechita is being performed. It must not be stabbed into the neck or buried by fur, hide, feathers, the wound itself, or a foreign object (such as a scarf) which may cover the knife. •
Hagramah (; cutting in the wrong location)
Hagramah refers to the location on the neck on which a kosher cut may be performed; cutting outside this location will in most cases disqualify a kosher cut. According to today's normative Orthodox practice, any cutting outside this area will in all cases disqualify a kosher cut. In order to avoid tearing, the kosher slaughter knife is expertly maintained and regularly checked with the ''shochet's'' fingernail to ensure that no nicks are present. 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."|alt=
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
tradition nowadays is to use a very sharp 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 their fingernail up and down both sides of the blade and on the cutting edge to determine if they can feel any imperfections. They then use 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
chalaf 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 universally accepted and is the only permitted blade allowed in religious communities.
Other rules The animal may not be
stunned prior to the procedure, An animal's "young" is defined as either its own offspring, or another animal that follows it around. 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==