Wikipedia is a wonderful (and answer-filled) thing!
Kosher
Traditional Jewish thought has expressed the view that all meat must come from animals which have been slaughtered according to Jewish law. These strict guidelines require the animal be killed by a single cut across the throat to a precise depth, severing both carotid arteries, both jugular veins, both vagus nerves, the trachea and the esophagus, no higher than the epiglottis and no lower than where cilia begin inside the trachea, causing the animal to bleed to death. Orthodox Jews argue that this ensures the animal dies instantly without unnecessary suffering, but many animal rights activists view the process as cruel, arguing that the animal may not lose consciousness immediately, and activists have called for it to be banned
Halal
The food must come from a supplier that uses halal practices. Specifically, the slaughter must be performed by a Muslim, who must precede the slaughter by invoking the name of Allah, most commonly by saying “Bismillah” (“In the name of God”) and then three times “Allahu akbar” (God is the greatest). Then, the animal must be slaughtered with a sharp knife by cutting the throat, windpipe and the blood vessels in the neck (while the animal is conscious), causing the animal’s death without cutting the spinal cord. Lastly, the blood from the veins must be drained.
Animals in normal slaughterhouses have an electrified bolt shot into their head. It might not be a pretty visual image but it guarantees a more reliable, painless and humane death.
I repeat: Fuck kosher and halal meats and adherents to those religions for not rejecting the barbaric traditions they demand.
