Mandatory labeling on all meat products stating if it was stunned, pre-slaughter

For example, meat sold in supermarkers, for example, be it a beef/veal or sheep meat, might have been slaughtered without the use of a stun-gun or other pre-stun method. Some religions do not allow the consumption of animal hind quarters, so that meat is then sold off to the general market where the general public, who might not wish to eat such a product, could unwittingly purchase it.