A cow is kosher when it meets two requirements: it has fully split hooves and it chews its cud. Cattle satisfy both criteria, making them a permitted species under Jewish dietary law. But a permitted species is only the starting point. The animal must also be slaughtered correctly, inspected for internal defects, and processed through several steps before the meat on your plate is actually kosher.
The Animal Itself: Split Hooves and Cud
The Torah lays out two physical signs that define a kosher land animal. First, its hooves must be completely split into two distinct toes. Second, it must be a ruminant, meaning it chews its cud by regurgitating and re-chewing food through a multi-chambered stomach. Cows, sheep, goats, and deer all qualify. Pigs have split hooves but don’t chew cud, so they’re excluded. Camels chew cud but lack fully split hooves. An animal must have both traits, not just one.
Beyond species, the individual animal matters too. A cow with certain injuries or diseases may be disqualified even though cattle as a species are permitted. That determination happens after slaughter, during inspection.
How the Animal Must Be Slaughtered
Kosher slaughter, called shechita, is performed by a trained practitioner using a specialized knife. The knife must be razor-sharp and perfectly smooth along its entire edge. Sharpening is done by grinding the blade against progressively finer whetstones, alternating sides, until the edge has no imperfections. Even a tiny nick in the blade disqualifies the slaughter entirely, because a flawed edge tears the tissue rather than cutting cleanly. If that happens, the meat is classified as nevelah (an improperly killed animal) and cannot be eaten.
The cut itself severs both the windpipe and the esophagus in a single, continuous motion across the throat. The practitioner cannot pause, press downward, or use a stabbing motion. These rules exist to ensure a swift death and rapid blood loss, since consuming blood is strictly prohibited in kosher law.
Inspecting the Lungs and Internal Organs
After slaughter, an inspector called a bodek examines the animal’s internal organs for defects that would render it treif (unfit). The lungs get the most attention because adhesions on the lung surface are the most common disqualifying defect in cattle.
The inspection happens in two stages. First, the inspector reaches through a cut in the abdominal wall and through the diaphragm to feel the lungs while they’re still inside the chest cavity. This tactile exam identifies any adhesions, which are abnormal attachments between sections of the lung or between the lung and the chest wall. Adhesions matter because they signal that a hole may exist in the lung, either one that was imperfectly sealed or one that could develop as the lungs expand and contract. A hole in the lung makes the animal treif.
After the initial feel, the lungs are carefully removed for visual inspection and then inflated to test for any hidden perforations. If the lungs pass both stages, the animal is approved.
What “Glatt” Actually Means
Glatt is a Yiddish word meaning “smooth,” and it describes a lung that has no significant adhesions. A glatt kosher animal’s lungs feel relatively smooth to the inspector and pass through the examination without issue. Under some rulings, adhesions that come off with an extremely gentle touch may still be permitted. But for young, tender animals like calves, lambs, or kids, the standard is stricter: no adhesions at all are tolerated. This is why all veal and lamb sold as kosher must meet a standard even beyond the typical glatt designation.
Today, “glatt kosher” is widely used as a general label suggesting a higher standard of kashrut, but its technical meaning specifically refers to the condition of the lungs.
Removing Forbidden Fats and the Sciatic Nerve
Even after an animal passes inspection, not every part of it is kosher. Certain internal fats, known as chelev, are forbidden to eat. These are hard, waxy fats found mostly around the kidneys, the stomach lining, and the hindquarters, distinct from the regular fat marbled through muscle tissue (which is permitted). A skilled butcher must carefully separate and remove all chelev.
The sciatic nerve running through the hindquarters must also be removed. This process, called nikkur (or porging), is so painstaking and labor-intensive that many kosher operations outside of Israel simply don’t sell the hindquarters at all. That’s a major reason kosher beef in the United States tends to come from the front of the animal: cuts like brisket, chuck, shoulder, and rib rather than sirloin or filet mignon.
Removing the Blood: Soaking and Salting
Jewish law prohibits consuming blood, so kosher meat goes through a specific process to draw it out. First, the meat is soaked in cold water for 30 minutes, then rinsed thoroughly. Next, coarse salt is applied on all surfaces and left for one hour. The salt draws residual blood to the surface. Afterward, the meat is rinsed three separate times in cold water to remove all the salt and extracted blood.
This process, called melichah, must happen within 72 hours of slaughter. If the meat sits longer without being salted, the blood is considered to have dried and set within the tissue, making it much harder to extract. Liver, which contains an especially high concentration of blood, cannot be made kosher through salting alone. It requires broiling over an open flame instead.
Certification and What the Symbols Mean
All of these steps require trained supervision at every stage. A mashgiach (kosher supervisor) oversees the process from slaughter through packaging to ensure nothing is missed. The final product carries a certification symbol from a rabbinical organization.
On packaging, you’ll see symbols like OU-Meat or OU-Glatt from the Orthodox Union, one of the largest certifying bodies. An OU-Glatt symbol indicates the animal’s lungs were smooth and free of significant adhesions. An OU-Meat (OU-M) symbol indicates the product contains meat or was produced on equipment shared with meat products, which matters because kosher law prohibits cooking or eating meat and dairy together. Meat certified kosher cannot be reheated on pans, dishes, or equipment that have been used for dairy, and doing so could render both the food and the utensils non-kosher.
Different certifying agencies have slightly different standards, which is why some consumers look for specific symbols they trust. The key distinction for beef is usually whether the product meets the glatt standard or a standard that permits minor, easily removable lung adhesions.