I am pasting most of an article from the website of Dr. Temple Grandin, who is a noted world authority on Animal Welfare and has designed slaughter houses and made numerous observations on slaughter methods on her website here,
http://www.grandin.com/ . She is probably almost as educated in this area as Castiel is on the NT and Quran.
This is taken from the page marked here,
http://www.grandin.com/ritual/euthanasia.slaughter.livestock.html
If you dont want to read the entire article with my highlighted emphasis my summation is:
Ritual Slaughter (specifically Kosher) is absolutely fine and animals did not appear to feel any pain. However, this was primarily contingent on the handling of the animal and the method of restraint prior to it's slaughter. Halal slaughter would seem to be fine on chickens, sheep and goats (this article was specifically on cattle) but the “halal” knife was too short for cattle. It recommended for Halal slaughter use the Kosher slaughter knife to prevent hacking and sawing or to prestun the cattle.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ritual slaughter is slaughter performed according to the dietary codes of Jews or Muslims. Cattle, sheep, or goats are exsanguinated by a throat cut without first being rendered unconscious by preslaughter stunning.
Because ritual slaughter is exempt from Humane Slaughter Act, some plants use cruel methods of restraint...
When ritual slaughter is being evaluated, the variable of restraint method must be separated from the act of throat cutting without prior stunning. Distressful restraint methods mask the animals reactions to the cut. (My emphasis)
The author designed and operated four state-of-the-art restraint devices that hold cattle and calves in a comfortable upright position during kosher slaughter. To determine whether cattle feel the throat cut, at one plant the author deliberately applied the head restrainer so lightly that the animals could pull their heads out. None of the 10 cattle moved or attempted to pull their heads out. Observations of hundreds of cattle and calves during kosher slaughter indicated that there was a slight quiver when the knife first contacted the throat. Invasion of the cattle flight zone by touching its head caused a bigger reaction. In another informal experiment, mature bulls and Holstein cows were gently restrained in a head holder with no body restraint.
All of them stood still during the cut and did not appear to feel it. Disturbing the edges of the incision or bumping it against the equipment, however, is likely to cause pain. Observations by the author also indicated that the head must be restrained in such a manner that the incision does not close back over the knife. Cattle and sheep struggle violently if the edges of the incision touch during the cut.
The design of the knife and the cutting technique appeared to be critical in preventing the animal from reacting to the cut. In kosher slaughter, a straight, razor-sharp knife that is twice the width of the throat is required, and the cut must be made in a single continuous motion. For halal (Muslim) slaughter, there are no knife-design requirements. Halal slaughter performed with short knives and multiple hacking cuts resulted in a vigorous reaction from cattle. Fortunately, many Muslim religious authorities accept preslaughter stunning. Muslims should be encouraged to stun the cattle or use long, straight, razor-sharp knives that are similar to the ones used for kosher slaughter.
Investigators agree that kosher slaughter does not induce instantaneous unconsciousness. In some cattle, consciousness is prolonged for over 60 seconds.
Observations by the author indicated that near immediate collapse can be induced in over 95% of cattle if the ritual slaughterer makes a rapid, deep cut close to the jawbone. Further observations indicated that calm cows and bulls lose sensibility and collapse more quickly than cattle with visible signs of agitation. The author has observed that cattle that fight restraint are more likely to have prolonged sensibility. Gentle operation of restraint devices facilitates rapid loss of sensibility.
Cattle do not appear distressed even when the onset of unconsciousness is delayed. Pain and distress cannot be determined by measurements such as an electroencephalogram. Behavioral observations, however, are valid measures for assessing pain. The author has observed that cattle appear unaware that their throat is cut. Investigators in New Zealand have made similar observations. Immediately after the cut, the head holder should be loosened slightly to allow the animal to relax. The author also has observed that after the head restraint is released, the animal collapses almost immediately or stands and looks around like a normal, alert animal. Within 5 to 60 seconds, cattle go into a hypoxic spasm and sensibility appears to be lost. The spasms are similar to those that occur when cattle become unconscious in a headgate that is used for restraint in feedlots. Practical experience has shown that pressure on the carotid arteries and surrounding areas of the neck from a V-shaped headgate stanchion can kill cattle within 30 seconds.
Even though exsanguination is not an approved method of euthanasia by the AVMA, the author has observed that kosher slaughter performed with the long, straight, razor-sharp knife does not appear to be painful. This is an area that needs further research. One can conclude that it is probably less distressful than poorly performed captivebolt or electrical stunning methods, which release large amounts of epinephrine.
Welfare can be greatly improved by use of a device that restrains the animal in a comfortable upright position. For cattle and calves, a conveyor restrainer or an upright restraint pen can be used. In small plants, sheep or goats can be held by a person. If an upright pen is used, vertical travel of the lift under the animal抯 belly should be restricted to 71 cm to prevent the animal from being lifted off the floor. A pressure limiting valve must be installed on the head holder and rear pusher gate. Many existing upright restraint boxes apply excessive pressure. To prevent excessive bending of the neck, the head holder should position the animal's forehead parallel to the floor. Equipping the head holder with a 15-cm wide, rubber covered forehead bracket will make the head holder more comfortable (Fig 3). The animal should stand in the box with its back level. An arched back is a sign of excessive pusher-gate pressure. In some plants, animals are removed from the restrainer before they become unconscious. Discomfort to the animal can be minimized by allowing it to lapse into unconsciousness before it is removed from the restrainer.
During the past five years, many large kosher slaughter plants for cattle have replaced shackling and hoisting with upright restraint. Large numbers of veal calves and sheep, however, are still shackled and hoisted. Progressive plant owners have installed upright restraint equipment, but
unfortunately there are some plant owners who still refuse to install humane restraint equipment because they are not legally required to do so. Animal handling guidelines published by the American Meat institute recommend the use of upright restraint.
Conclusions
The technology exists that allows slaughter and euthanasia to be one. Although some slaughter plants maintain high animal welfare standards, there are others in which management allows abuses to occur.
After adequate equipment has been installed, the single most important determinant of good animal welfare is the attitude of management. Good equipment provides the tools that make humane slaughter and handling possible, but it is useless unless it has good management to go with it.