Key takeaways
- By-product describes the supply chain, not safety: parts like liver, kidney or tripe that do not usually reach human plates in a given market.
- EU pet food may only use category 3 material, from animals passed as fit for human consumption at slaughter. Roadkill, waste and diseased animals are excluded by law.
- Organ meats are often more nutrient-dense than the muscle cuts people prize, which is why they earn their place in a recipe.
- The fair criticism is transparency: "meat and animal derivatives" is legal and safe, but it cannot tell you which species is in the bowl.
What a by-product actually is
When an animal is slaughtered for human food, people buy some parts of it and not others. What counts as "the good parts" is cultural, not biological: liver, tripe, kidneys and chicken feet are everyday human food in large parts of the world and unwanted in others. The parts a market does not route to human plates are by-products of producing the parts it does.
That is the whole meaning of the word. It describes a position in the supply chain, not a statement about safety or nutritional worth. A chicken liver is a by-product in a supermarket that cannot sell chicken livers, and dinner two streets away.
Pet food is where much of this material goes, and that is by design rather than by neglect. Dogs and cats have no concept of a premium cut, and some of what humans skip is nutritionally better than what they keep.
The rules behind the word
In the EU, animal by-products are governed by Regulation 1069/2009, which sorts all animal material not destined for human consumption into three categories by risk. Category 1 and 2 material, which includes anything from diseased animals or animals that died outside slaughter, must not enter pet food at all. Pet food may only use category 3 material: parts from animals that were inspected and passed as fit for human consumption at the time of slaughter.
FEDIAF, the European pet food federation, puts the same rule in plain words: ingredients must come from animals that passed veterinary inspection as fit for human consumption at slaughter, and waste products, roadkill and diseased animals cannot be used.
It is worth letting that land, because it inverts the internet's favourite image. The by-products in an EU pet food come from the same inspected animals as the meat counter. The parts differ; the animal does not.
What they bring nutritionally
Organ meats are dense food. Liver carries vitamin A, iron, copper and B vitamins at levels muscle meat does not approach. Heart is rich in taurine, the amino acid cats cannot do without. Tripe, lungs, and the trimmings left after filleting fish all carry protein and fat worth eating. FEDIAF describes this material as an excellent source of protein and essential amino acids, which matches what any nutrient table will tell you about organ meat.
Rendered versions appear on labels too. A meat meal is animal by-product that has been heat treated and dried, with most of the moisture and fat removed, leaving a concentrated protein source. Meal is not a euphemism for poor quality; it is a processing description, and gram for gram a good meal carries more protein than fresh muscle, because the water is already gone.
None of this makes a food good by itself. A recipe stands or falls on its full nutrient profile against the adequacy statement, which is why the complete-or-complementary line outranks any single ingredient, flattering or scary.
"Meat and animal derivatives", decoded
EU labelling rules give manufacturers a choice: list each feed material by its name, or group ingredients into legal categories. "Meat and animal derivatives" is the category covering flesh and other parts of warm-blooded land animals, which is why the phrase appears on so many packs. Using it is lawful and, as FEDIAF notes, it exists because labelling legislation defines it, not as a mechanism for hiding ingredients.
The category system has one genuinely useful corollary. When a pack highlights a flavour, "with chicken" or "rich in beef", EU rules require the label to state the percentage of that highlighted ingredient. That small number in the composition list is one of the few places where marketing is forced into arithmetic.
So the phrase is not a red flag for safety. What it is, is a low-resolution label. "Meat and animal derivatives (4% chicken)" tells you the recipe contains at least 4 percent chicken and an unspecified mix of other approved animal material, which may vary batch to batch. For most healthy pets that variation is irrelevant. For some situations, it is the whole problem, which brings us to the fair criticism.
Where scepticism is actually warranted
If your pet needs a specific protein kept out of the bowl, a category label defeats you. Suspected food allergies are usually reactions to particular proteins, chicken and beef among the common ones, and an elimination diet only works when you can control exactly which animals are in the food. "Meat and animal derivatives" cannot promise that, however safe the material is.
Transparency also has a quieter, everyday value. A label that says "chicken (26%), chicken liver (10%)" has committed itself: the manufacturer is naming sources and proportions that can be checked. A label that leans entirely on categories has kept its options open. Neither is unsafe, but they are not equally informative, and given two otherwise similar foods, the one that tells you more deserves the benefit of the doubt.
This is exactly how Snuffo treats the subject. The app does not mark a food down for containing by-products, because the evidence gives no reason to. It does look at how much the label discloses about its sources, because that is the part a shopper can verify and the part a manufacturer controls. The details live in our ingredient-list guide and the methodology.
Three myths, answered quickly
- "By-products means roadkill, waste, or dead pets." In the EU this is excluded by law. Only category 3 material, from animals passed fit for human consumption at slaughter, may be used in pet food, and FEDIAF states plainly that waste, roadkill and diseased animals cannot be.
- "By-products cause allergies." Food allergies are reactions to proteins from particular species, and a pet allergic to chicken reacts to chicken breast as surely as to chicken liver. The relevant question is which animal, not which part.
- "A food without by-products is automatically better." The recipe with liver in it may out-nourish the one built from muscle meat alone, and both stand or fall on the full profile. "No by-products" on the front of a pack is a marketing sentence, not a nutritional one.
Frequently asked questions
Are animal by-products bad for dogs and cats?
No. EU pet food may only use category 3 material, from animals passed as fit for human consumption at slaughter, and organ meats are often more nutrient-dense than muscle. Judge the food on its full recipe and adequacy statement, not on this word.
What does "meat and animal derivatives" mean?
A legal category name that EU labelling rules allow instead of naming each animal ingredient. It covers flesh and other parts of warm-blooded land animals. Safe, lawful, and low-information: it does not say which species or parts are inside.
Are by-products roadkill or diseased animals?
Not in the EU. Regulation 1069/2009 keeps category 1 and 2 material, including diseased animals and animals that died outside slaughter, out of pet food entirely. FEDIAF is explicit that waste, roadkill and diseased animals cannot be used.
Why do manufacturers use by-products at all?
They carry a lot of nutrition per gram, they cost less than cuts humans compete for, and using them means more of each animal is eaten rather than discarded. To a dog or a cat, a liver is not a lesser ingredient.
How do I avoid a specific protein if the label says "meat and animal derivatives"?
From that wording alone, you cannot, because the mix of species can lawfully vary. Avoiding a specific protein needs foods that name their animal sources, and a real elimination trial belongs under veterinary guidance.
