Eating the kosher types of animals and birds is allowed only after they have been properly slaughtered; see Ch.3. It is forbidden to eat them if they die or are killed in any other way, or to eat parts of their bodies that are removed (see 14:6) or become detached (see 55:5) while they are still alive (62:1-4, and see next paragraph), but parts removed from them after slaughtering may be eaten as soon as they have died (27:1). Fish and locusts do not require slaughter (13:1;85:2) but they should not be eaten while they are still alive.
Anything edible (see 81:3-4;84:17;85:3) that is derived from a forbidden source is forbidden, but human milk (81:7) and bees’ honey (81:8-9) are permitted. The milk and eggs of a kosher species are permitted even though they come from a living creature (81:5;86:4). The milk and eggs of a TEREFAH (see Ch.4) are forbidden (81:1,6;86:3,10), but a living offspring of a TEREFAH is permitted (79:3; see 86:7). The oral Torah gives signs that distinguish the eggs of kosher and unkosher species (83:8;86:1-2); these signs are used when the parentage of the egg is not known. Birds’ eggs are forbidden if they have started to develop (66:7;86:8).
It is forbidden to take the eggs or non-flying chicks of a kosher bird if a kosher mother bird is just above them (see 292:1,7-9,11-13), but it is permissible to kill them (see 292:10) or to take them if the mother bird is first sent away in condition to fly (292:4-6). This prohibition does not apply if the birds are in a location easily accessible to the taker; see 292:2-3.
A kosher creature that eats only forbidden foods is forbidden (60:1). If it is sick or has eaten or absorbed a poisonous substance it is forbidden only if the substance is dangerous to humans (60:1-2). Indeed, any dangerous situation must be avoided (116:5; see also Ch.12). Substances that the sages considered to be dangerous included snake venom (116:1), meat and fish that were cooked together (116:2-3), and human sweat (116:4-5). It is also forbidden to eat disgusting foods and to eat with dirty hands or utensils (116:6). It is forbidden to regularly buy or sell foods that are Biblically forbidden even if deriving benefit from them is permitted; the only exception is CHELEV (117:1; see below). On procedures to follow if forbidden foods were accidentally or deliberately sold to a Jew see 119:13-15.
The blood of animals and birds is forbidden (66:1) even after they are slaughtered unless it remains absorbed in the meat (67:1-5). Procedures for removing the blood from meat are described in Ch.5. A “blood spot” found in a bird’s egg is rabbinically forbidden, and in some cases is an indication that the egg has started to develop (66:2-3,5,7). Fishes’ blood is forbidden only if it might be confused with animal or bird blood (66:9), and one’s own blood is permitted if it has not left the body (66:10). On mixtures and doubtful cases see 66:4,8.
The sciatic nerve (GID HA-NASHEH) is forbidden even after slaughter in animals and in birds that have round thigh sockets (65:5-7). On doubtful cases and trustworthiness see 65:11-14; on the extent of the nerve see 65:8-9. Certain parts of the fat (CHELEV) of cattle, sheep, and goats are forbidden even after slaughter; see 64:1-15. The oral Torah gives signs (involving the structure of the horns) that distinguish these animals (which are called BEHEMAH) from other kosher animals (CHAYAH) whose fat is permitted; these signs are used if the species is not known (80:1-6). Removal of these forbidden parts requires great skill and must be learned by observing an expert (64:7). It should be done within three days after slaughtering (64:18).
Shulchan Aruch, Copyright (c) 2000 ProjectGenesis, Inc.