After the slaughtering, the internal organs of cattle and fowl are examined for
potentially fatal diseases or injuries, such as adhesions (sirchot) in the lungs or holes in the stomach. The occurrence of any one of dozens of specified tereifot, as these defects are called, renders the entire animal not kosher.
Nikur ("deveining") involves removing certain forbidden veins and fats from cattle. They are
extremely prevalent in the hindquarters, and due to the complexity involved in
their removal, this part of the animal is generally not sold as kosher.