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Many pet parents have heard of by-products and meat meal, but few truly understand what these ingredients are. Some pet owners wonder why they are in pet food, or if they are even healthy for our animals. For many people, these words have a very negative connotation and are considered low-quality ingredients or poor sources of nutrition. Pet food companies have added to the confusion by marketing to pet owners’ fears, selling products claiming to have no by-products or meat meal. Pet parents are worrying that they need to avoid these common ingredients, but this is truly unnecessary, as they can actually provide great sources of nutrition to our canine and feline companions.
What is meat?
Meat is defined by AAFCO as “the clean flesh derived from slaughtered mammals and limited to that part of the striate muscle which is skeletal or that part which is found in the tongue, in the diaphragm, in the heart or in the esophagus; with or without the accompanying and overlying fat and portions of the skin, sinew, nerve and blood vessels which normally accompany the flesh.” In short, meat is just skeletal muscle of mammals. It does not contain bone, internal organs, hair, hooves, or horns. The simple term “meat” can be used to describe muscle tissue from cattle, swine, sheep, or goats. Meat from other mammals must be listed with their species name.
Poultry is another ingredient that may be listed on a pet food label. Poultry is defined as “the clean combination of flesh and skin with or without accompanying bone, derived from the parts or whole carcasses of poultry or a combination thereof, exclusive of feathers, heads, feet and entrails.” Poultry, unlike mammalian meat, may contain bone. However, it does not contain internal organs, feathers, heads, feet, or beaks.
What are by-products?
By-products are defined by AAFCO as “secondary products produced in addition to the principal product.” A “principal product” is what the animal was originally slaughtered for: with food production animals, they are principally used for meat or poultry. Typically, the principal product is for human consumption. A by-product is therefore anything that comes from the animal which does not fall under the definition of meat or poultry. Technically things like leather, hair, and hooves are by-products, but they are used for non-food purposes (e.g., textiles, paintbrushes, and glue). Here’s where it gets tricky: AAFCO’s definitions of by-products become a bit more specific than the general use of the term.
AAFCO defines meat by-products as “the non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially de-fatted low temperature fatty tissue and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hoofs.”
AAFCO defines poultry by-products as “non-rendered clean parts of carcasses of slaughtered poultry, such as heads, feet and viscera, free from fecal content and foreign matter except in such trace amounts as might occur unavoidably in good factory practice.”
Generally, by-products contain the nutrient-dense organ meats of animals.
What is meat meal?
AAFCO defines meat meal as “rendered product from mammal tissues, exclusive of any added blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents except in such amounts as may occur unavoidably in good processing practices.”
Meat and bone meal follows the same definition, but includes bone as well.
What is rendering?
Rendering is a type of complex cooking process in which animal tissues are heated to extreme temperatures. Then, different nutrients are separated out: protein, fat, moisture, and minerals. Rendered products are used to create meat meal (containing the protein from the rendered tissues), tallow or lard (fat from cattle or swine, respectively), and mineral mixtures (usually from bone meal). Rendered products are extremely concentrated sources of nutrients (protein, fat, or minerals) because they lack water.
What is by-product meal?
Animal or poultry by-product meal are simply rendered by-products from mammals or poultry, respectively. Again, these products provide concentrated sources of nutrition.
Are by-products and meat meal "fillers"?
“Fillers” is a term commonly used to describe certain ingredients in a diet. It is usually used to describe sources of fiber and carbohydrates, but some people also refer to by-products as fillers. The term “filler” is often used to demonize certain ingredients, because whomever is using the term believes they are poor sources of nutrition. However, this term is not defined by AAFCO and therefore has no formal or legal definition.
By-products and meat meal are not “fillers” by any use of the word. They provide concentrated sources of nutrition that are essential in your pet’s diet.
To learn more, visit Grains as “fillers”.
Are by-products and meat meal good for pets?
While by-products may seem unappetizing to most Americans, they are considered delicacies in many other parts of the world. They are packed with nutrients and are very healthy when eaten in the right amounts. By-products provide pets with sources of nutrition from animal sources other than skeletal muscle meat.
The process of rendering may sound disgusting to many pet owners, but it is essential in creating an edible product from an otherwise inedible tissue. Rendering creates concentrated meat meals or bone meals that are packed with vital nutrients your pet needs to live.
Remember the difference between nutrients and ingredients: Nutrients are essential components of the diet such as protein, fat, minerals, and vitamins. Ingredients are merely the sources of these nutrients. Just because certain nutrition comes from a less desirable source than muscle meat doesn’t mean it is less healthy!
To learn more about nutrients, visit Nutrient requirements.
Why are by-products and meat meal in pet food?
Muscle meat can be deficient in many nutrients and have unbalanced nutrition. Feeding a pet solely muscle meat or poultry would be detrimental to his health, because he requires many more nutrients than are found in muscle meat. By-products and meat meal can help balance out the nutrition a pet is receiving. Meat meal is especially good for balancing a diet because it contains such concentrated nutrition; a small serving of meat meal can provide more nutrition than muscle meat or by-products alone.
Meat meal and by-products are also less expensive forms of nutrition than skeletal muscle meat or other ingredients. This is because these products are considered undesirable for human consumption, so there is very little market competition for them.
There needs to be a market for these ingredients because otherwise, the “undesirable” parts of the animal would get thrown away, leading to a large amount of food waste and environmental contamination. Using rendered animal tissues and by-products to make pet food and other goods is an awesome form of recycling.
Do pet foods contain "the 4 Ds"?
There is a lot of hype surrounding the misguided theory that commercial pet foods (namely kibble) are chock-full of “the 4 Ds”: dead, dying, diseased, or disabled (down) animals.
Per the FDA, animals who died from causes other than slaughter are considered “adulterated” and are not directly suitable to be used for animal feed. This usually includes animals who died from disease or natural causes. However, they may be used in animal feed if they are free from chemical additives and have been heat treated (rendered) to ensure they do not contain disease-causing microorganisms.
Again, remember the difference between ingredients and nutrients. Once the animal’s tissues have been rendered, they are now separated out into nutrients. As long as the end products do not contain disease-causing microbes, it is safe for your pet to eat. Pets’ digestive systems do not know or care about the source of the nutrients they are receiving; they only care about whether they can digest and use these nutrients.
It may be unappetizing to think about, but the bodies of animals who are dying or diseased would otherwise end up going to a landfill, cremated, or buried in the ground, where they could cause extensive damage to the environment. Using the rendered products from these animals for the manufacture of pet food can be a safe, inexpensive source of nutrition.
Reliable, trustworthy pet food manufacturers will always have a good relationship with the suppliers of the ingredients they use to make their pet food. They will know where their meat meal is coming from, and they may have strict regulations in place for sourcing these ingredients. If you have questions, feel free to call your pet food manufacturer and find out where they source their meat and bone meal. (Learn more about reliable pet food manufacturers and quality control in How to pick a pet food, part 1.)
Should I avoid by-products and meat meal?
Avoiding these ingredients is nearly impossible, and it is absolutely unnecessary to do so. By-products and meat meal are packed with nutrition and provide balance to pet foods, as stated above.
Some manufacturers or other entities may try to convince pet owners that by-products and meat meal are unhealthy or provide inferior sources of nutrition.
If you experience this coming from a manufacturer, it should be a red flag, because they are using fear-based marketing to sell their “superior” food to you. Nearly all pet foods contain by-products or meat meal, they might just use more appealing terminology, such as specific organ names (e.g., liver, lung, kidney) or simply “organ meat.”
If you experience this coming from an outside entity such as a pet food rating website or from someone claiming to be an expert in pet nutrition (but has no formal education in the subject), this tells you the person is ill-informed, and you should probably not listen to their unsubstantiated claims.
Resources
AAFCO: “Byproducts”
AAFCO: “What’s in the ingredients list?”
Ann Wortinger and Kara Burns: Nutrition and Disease Management for Veterinary Technicians and Nurses, second edition (2015). Page 144.
Cattle Empire: “The many uses of a cow – beef by-products”
EPA: “Meat rendering plants”
Tufts University: “Don’t be bothered by by-products”
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