An animal product is any material derived from the body of an animal. Examples are fat, flesh, blood, milk, eggs, and lesser known products, such as isinglass and rennet.
Animal by-products, as defined by the USDA, are products harvested or manufactured from livestock other than muscle meat. In the EU, animal by-products (ABPs) are defined somewhat more broadly, as materials from animals that people do not consume. Thus, chicken eggs for human consumption are considered by-products in the US but not France; whereas eggs destined for animal feed are classified as animal by-products in both countries. This does not in itself reflect on the condition, safety, or wholesomeness of the product.
Animal by-products are carcasses and parts of carcasses from slaughterhouses, animal shelters, zoos and veterinarians, and products of animal origin not intended for human consumption, including catering waste. These products may go through a process known as rendering to be made into human and non-human foodstuffs, fats, and other material that can be sold to make commercial products such as cosmetics, paint, cleaners, polishes, glue, soap and ink. The sale of animal by-products allows the meat industry to compete economically with industries selling sources of vegetable protein.
The word animals includes all species in the biological kingdom Animalia, including, for example, tetrapods, arthropods, and mollusks. Generally, products made from fossilized or decomposed animals, such as petroleum formed from the ancient remains of marine animals are not considered animal products. Crops grown in soil fertilized with animal remains are rarely characterized as animal products. Products sourced from humans (ex; hair sold for wigs, donated blood) are not typically classified as animal products even though humans are part of the animal kingdom.
Several popular diet patterns prohibit the inclusion of some categories of animal products and may also limit the conditions of when other animal products may be permitted. This includes but not limited to secular diets; like, vegetarian, pescetarian, and paleolithic diets, as well as religious diets, such as kosher, halal, mahayana, macrobiotic, and sattvic diets. Other diets, such as vegan-vegetarian diets and all its subsets exclude any material of animal origin. Scholarly, the term animal source foods (ASFs) has been used to refer to these animal products and by-products collectively.
In international trade legislation, the terminology products of animal origin (POAO) is used for referring to foods and goods that are derived from animals or have close relation to them.
Slaughterhouse waste is defined as animal body parts cut off in the preparation of carcasses for use as food. This waste can come from several sources, including slaughterhouses, restaurants, stores and farms. In the UK, slaughterhouse waste is classed as category 3 risk waste in the Animal By-Products Regulations, with the exception of condemned meat which is classed as category 2 risk.
The leftover pieces that come from the process of stripping meat from animals tends to get used for different purposes. One of them is to put these parts into pet food. Many large, well-known pet food brands use animal by-products as protein sources in their recipes. This can include animal feet, livers, lungs, heads, spleens, etc or an admixture in the form of meat and bone meal. These organs are usually not eaten by humans depending on culture, but are safe and nutritious for pets regardless. By-products can also include bad-looking pieces. They are always cooked (rendered) to kill pathogens. Some pet food makers advertise the lack of by-products to appeal to buyers, a move criticized for contributing to food waste and reducing sustainability.