PETA has never stood on reputable science when they can use photoshop and a film editor to gain soccor mommy sympothy.
From:
The Welfare of Pigs During Transport and Slaughter
Temple Grandin
Department of Animal Science
Colorado State University
Fort Collins CO 80523-1171
http://www.grandin.com/references/pig.welfare.during.transport.slaughter.htmlStunning Methods
Electric Stunning
To induce instantaneous insensibility, electrical stunning must induce an epileptic state by passing an electrical current through the pig’s brain (Hoenderken, 1978, 1983; Warrington, 1974; Croft, 1952, Lambooij et al., 1996, and Gregory, 1998). There are two basic types of electrical stunning. Head only where the tongs are placed across the head and cardiac arrest where a current is passed through both the head and heart. Head only stunning is reversible and the pig will return to sensibility unless bled quickly. Cardiac arrest stunning will kill most of the pigs by stopping the heart. For pigs, the amperage that is required to induce epilepsy is 1.25 amps (Hoenderken, 1978-1983). There also must be sufficient voltage to deliver the current. The recommended minimum voltage is 250 volts (Troeger and Woltensdorf, 1989).
To reduce blood splashing (petechial hemorrhages) in the meat, some slaughter plants use high frequency stunning. However, too high of an electrical frequency of 2000 to 3000 hz failed to induce instantaneous insensibility (Warrington, 1974, Croft, 1952, Van derWal, 1978). Fifty cycles which is the regular mains electrical frequency was the most effective (Warrington, 1974). Anil and Mckinstry (1994) found that 1592 hz sine wave or 1642 hz square wave head only stunning at 800 ma induced seizure activity in small pigs. The main disadvantage is that at frequencies above 50 hz return to sensibility will occur more quickly (Anil and McKinstry, 1994). Due to kicking, high frequency head only stunning is not practical unless it is combined with an additional current to stop the heart. Eight hundred hz head only stunning in conjunction with a 50 hz current applied to the body is effective (Berghaus and Troeger, 1998; Lambooij et al., 1996 and Wenzlawowicz et al., 1999). This system is available in commercially built equipment.
Most plants in the U.S. apply a single current passed from the head to the body. It is essential to apply sufficient current to induce both cardiac arrest and an epileptic seizure. The author has observed large sows where sufficient current was applied to induce cardiac arrest but insensibility was not induced. In this situation, the sows had natural spontaneous blinking five seconds after stunning which later disappeared due to cardiac arrest (Grandin, 2001). Raising the amperage to greater than 1.25 amp eliminated blinking in sows. The blink looked like the blink of an unstunned pig and it was not rapid nystagmus.
Electrodes must be placed in the correct position to put the brain in the current path (Croft, 1952; Warington, 1974; Anil and McKinstry, 1998). Placing the electrodes too far back on the neck will result in a shorter period of insensibility (Velarde et al, 2000). Grandin (2001a) observed that placing the head electrode of a cardiac arrest stunner too far back on the neck resulted in blinking pigs. Placing the electrode in the hollow behind the ear eliminated the eye reflexes.
Electronic systems are now available to control amperage surges that cause petechial hemorrhages and monitor how well the operator applies the stunning tongs. Gregory (2001) monitored the electrical tracings of stuns to detect problems such as poor initial contact with the animal or interrupted stuns. He concluded that animal welfare problems occurred in about 9% of the stuns. Ross (2002) has developed an electronic microprocessor system that controls waveform, frequency and stun time. This computerized system also records operator errors that would compromise pig welfare such as interrupted stuns and energizing the electrode before it is in full contact with the pig. Unpublished data collected from these computers indicate that stunner operator errors due to fatigue greatly increase after 2 hours. Premature energizing of the electrode will cause squealing. Squealing is correlated with physiological indicators of stress (Warriss et al., 1994). White et al. (1995) reports that squealing is associated with discomfort.
Grandin (2001a) has found that problems with return to sensibility after electrical stunning can be easily corrected. The most common causes of problems with return to sensibility were wrong position of the tongs and poor bleeding technique (Grandin 2001a). Improving the ergonomic design of the head to back cardiac current stunning tongs or the employee’s work station, eliminated problems with return to sensibility.
