Eating the Dead: Pet Food Only a Zombie Could Love; The Circular Madness of Upcycling Dead, Dying, and Diseased Animals into Food for Animals

Have you ever wondered, before you tuck into that BLT, what the pig you’re eating used to eat?  Considering the animal feed industry is poised to start using fly larvae protein [AKA maggots] in animal feed, I thought you’d like to know what do animals that are raised for their meat eat?

I think making animal feed out of worms is a marvelous idea. After all, worms, grubs, and insects are an excellent source of protein – just ask anyone who eats them. And the beautiful thing about raising bugs for food is that means that less of the truly disgusting sh*t won’t be fed to animals.

Practically speaking, eating worms is not all that different from the rendered remains of the maggot encrusted, parasite infested, bloated carcasses already in animal feed. Now, they’ll just be getting the maggots – a la cart – which, hopefully, haven’t just recently dined on the decaying, putrefying flesh of another animal. But I’m pretty sure the fine distinction between what a maggot ate before it gets eaten by someone higher up on the food chain is probably not a difference many diners would care to argue over.

Soupçon of Carrion

Putting aside the ethical and moral problem of feeding maggots to livestock for a sec, you’re probably wondering how the hell do bloated carcasses end up in animal feed in the first place. Those carcasses are known as deadstock (not livestock), and farmers, animal shelters, and veterinarians throughout the U.S. are highly dependent on the rendering industry as methods of disposal for dead animals. In essence, animals that die of disease, old age, are euthanized and then rendered into meat and bone meal and animal fat that is used to make animal feed and pet food.

Despite FDA’s stamp of approval (by way of a compliance policy) of using non-slaughtered animals in food for animals, alternatives to rendering are limited. The question becomes what to do with the millions of animals that die on farms every year?

Recycling Dead Animals is a Bitch

Ideally, composting is the preferred method of legally disposing of these materials; however, many states ban burning, burying, and, for the most part, composting deadstock (some states only allow for the composting of poultry, but not mammals), so alternatives to rendering are limited.

That’s where the rendering industry comes in. The rendering industry is supposed to abide by state laws regarding deadstock disposal, which establish a time limit within which the disposal must take place (usually 24 or 48 hours after death) to avoid the nuisances associated with odors, and the potential transmission of disease-causing pathogens from the carcasses.  But, sometimes, that doesn’t happen. In fact, it may be several days before the animal can be removed.

Fraîche Carcasse

For many reasons, it is not always practical or feasible to have deadstock picked up and removed and processed within a narrow time frame. In an article about a renderer in California, the Sacramento Rendering Company, it describes what happens inside a rendering plant after picking up the deadstock (videos below):

“…there, on the concrete floor, is a 5-foot-high pile of dead and bloated dairy cows. They’d been dumped in a heap off a truck that morning. They’ll be skinned, cooked, compacted and sent back to market as pet food or poultry feed.”

Cuisine de Charogne

The problem of disposing of dead animals in the U.S. is a confusing patchwork of contradicting rules. Depending on the reason for death, natural, disease, or euthanasia, regulations vary widely.

Overall, the preference is to render the animal carcasses; however, if the animal was euthanized, drug residue survives the rendering process undegraded. Then there are prions from Mad Cow disease that are heat stable and are not destroyed by the rendering process. Additionally, there are other compounds that are not degraded by cooking, like carcinogenic biogenic amines, such as cadaverine and putrescine, are heat stable, and survive the rendering process as well.

Road Kill à la Carte

And then there’s the roadkill. Where do think all those animals go? Little fairies that manage road-kill on state and local roads have limited options: Incineration or rendering. Disposal of roadkill by burial and composting of roadkill on public or private lands is not allowed in most states. Likewise, landfills do not knowingly accept dead animals. Therefore, rendering of dead deer, bear, skunks, raccoons, moose, elk, and buffalo is accomplished by renderers.

Early Bird Special: Mass Casualties

Managing animal mortalities is a significant problem for emergency and routine production of animals. Disease containment strategies (i.e., 3D or depopulation, disposal, and decontamination) are critical protocols needed to protect humans and animals against high consequence diseases. Aside from incineration, rendering is sometimes the only viable option when dealing with mass mortalities. Many states say that rendering is the preferred means of animal disposal because it “offers a relatively safe and integrated system that complies with the fundamental requirements of environmental quality and disease control.”

Braised Brains Avec Gruyere

Cows are not allowed to be fed to other cows, for fear of transmitting Mad Cow Disease, otherwise known as Bovine Spongiform Encephalopathy (BSE). FDA feed rule forbids cattle older than 30 months of age being rendered for use in animal food – including pet food – unless the specific risk materials (SRM) – brain and spinal cord – are removed first. Some renderers claim to pick up only cattle less than 30 months of age, and they require farmers to produce some proof of age, such as records or using teeth to calculate age. And then there are renderers who just don’t give a sh*t and will take all animals, claiming they segregate them by age. If they have the facilities, those renderers will remove the brains and spinal cords from the older cattle, if they don’t, then the entire carcass is rendered together. Presumably, none of the rendered material containing the SRM is sold or used for animal feed. But realistically, separating SRM from decaying carcasses is not feasible or practical, so don’t hold your breath waiting for that to happen.

Soupe de Chien et Chat

Euthanized pets in pet food? The pet food industry’s worst public relations nightmare. After a former AAFCO president unwisely admitted Fluffy could be in Fido’s dinner, consumers really began to worry. FDA worried too, particularly when sodium pentobarbital (the drug used to euthanize pets) was discovered in dog food, and they developed a test based on the assumption that the origin of the pentobarbital was from euthanized dogs and cats.  But the trouble with their test was, it didn’t work. Therefore, FDA concluded they assumed “the pentobarbital residues are entering pet foods from euthanized, rendered cattle or even horses.”

Even so, the levels of pentobarbital residue were found to be so low that the CVM concluded that “it is highly unlikely a dog consuming dry dog food will experience any adverse effects from exposures to the low levels of pentobarbital.”

Despite FDA’s suggestion that it could have been a euthanized horse or a cow, veterinarians know they are forbidden to use euthanizing drugs to kill livestock because the drugs may end up in the food chain. The instructions on the labels of euthanizing drugs state:

“Not for use in animals intended for food.”

The AVMA does not recommend using barbiturates as a means of euthanizing stock as the carcass of barbiturate-treated animals is considered “unfit for human or animal consumption. Ingestion by wildlife or other animals can induce toxicities.”

Cornell University concluded that “rendering is not an acceptable form of disposal, as the rendering process does not eliminate pentobarbital from the tissue (O’Connor et al. 1985).”

The U.S. Department of Fish and Wildlife agrees:

“Rendering is not an acceptable way to dispose of a pentobarbital-tainted carcass. The drug residues are not destroyed in the rendering process, so the tissues and by-products may contain poison and must not be used for animal feed. Finally, note that regulations may change as lawmakers seek to balance growing concerns over biosecurity and transmissible spongiform encephalopathies with the ongoing need for environmental protection.” (U.S. Fish and Wildlife Factsheet, attached)

Because euthanizing drugs are an environmental hazard – contamination of groundwater and soil is possible if the carcasses are buried or composted – and there is a danger of wild animals scavenging on euthanized carcasses, therefore rendering is the preferred method of disposal.

FDA, aware of this risk, added the following environmental warning to all animal euthanasia drugs:

Environmental Hazard: This product is toxic to wildlife. Birds and mammals feeding on treated animals may be killed. Euthanized animals must be properly disposed of by deep burial, incineration, or another method in compliance with state and local laws, to prevent consumption of carcass material by scavenging wildlife.”

Despite the environmental warning, the FDA has no plans to take a stand on eliminating euthanizing drugs from pet foods and animal feed, as long as only trace amounts are found food for animals. Until more testing is done, the source of the animal species responsible for the contamination will never be discovered.

Grilled chicken, my eye

Next time you’re contemplating a decision in the pet food aisle, don’t let the images of grilled chicken breasts on the barbeque fool you, because most of what makes up the dog and cat food originated from a rendering plant and chances are it includes some of the cooked remains of animals that died in the field, were hit by a car or euthanized by a vet.



p style=”text-align: justify;”>The fate of Sodium Pentobarbital in Rendered Products
Animal Rendering Fact Sheet LA County 2004
LA county renewal of the contract with West Coast Rendering to 2019

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Mollie Morrissette

Mollie Morrissette, the author of Poisoned Pets, is an animal food safety expert and consumer advisor. Help support her work by making a donation today.

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