Bovine respiratory tracts were examined for blood following shechita and halal slaughter without stunning, and captive bolt stunning with sticking. In all three methods the cattle were in the upright position at the start of the bleeding. Those that had not been stunned continued to breathe during the early part of bleeding whilst those that were stunned were not breathing. Nineteen percent of the shechita, 58 % of the halal and 21 % of the stunned plus stuck cattle had blood lining the inner aspect of the trachea. Thirty sex percent, 69 % and 31 % had blood in the upper bronchi. Ten percent, 19 % and 0 % had blood – tinged foam in the trachea. It was concluded that concerns about suffering from airway irritation by blood could apply in animals that are either not stunned before slaughter or do not lose consciousness rapidly whilst blood is present in the respiratory tract.
Neville G., Gregory, Wenzlawowicz, von Holleben (2009): Blood in the respiratory tract during slaughter with and without stunning in cattle, Meat Science 82
