Our Squeamishness About Food Is Harming Our Animals

Wild Things
Slate’s animal blog.
Jan. 3 2014 10:14 AM

Let Them Eat Carcass

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A Sumatran tiger licks a fancy feast at the La Fleche zoo in France: an ice block flavored with chicken and rodent.

Photo by Jean Francois Monier/AFP/Getty Images

We Americans have a funny relationship with food. We may not be apex predators, scientifically speaking, since we augment our meat with grains and plants, but we are predators all the same. But most of us haven't the slightest idea about the magical transformation by which cow becomes beef. The modern supermarket provides us with something called "psychological distance" between ourselves and our food, allowing us to abstract away the cows, pigs, chickens, turkeys, fish, and all the other critters at the other end of the meat industry. Few of us know how to butcher a chicken, feathers and feet and all, let alone how to ethically, safely slaughter it.

That psychological distancing has crept into the way we feed our animals as well. Cats, for example, are obligate carnivores, meaning that they need meat to survive. Their domestication began because it was handy to keep them around for their natural rodent-hunting abilities. And yet we'd rather our housecats eat processed food from a can than go hunting. We might think it's gross and unseemly when the cat drags in a dead pigeon or lizard, but cats are predators. So why not provision the housecat with the occasional humanely slaughtered sparrow carcass? Why not let the dog eat an ethically dispatched squirrel?

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Setting aside the environmental damage our pets can wreak on local wildlife, maybe our discomfort arises because we don’t want to know all that much about what our carnivorous pets are eating, either.

Our moral condemnation and visceral disgust over animals acting like animals even extends to cats at the zoo. We love seeing the lions and tigers. But do we necessarily want to see them act like lions and tigers?

The big cats are not kept on a vegetarian diet. But, as with our housecats, the meat they usually get is unrecognizable as such. They're being fed with the animal equivalent of TV dinners. Pre-packaged and heavily processed, it might be described in the scientific literature as "formulated foodstuffs." One common commercial feline diet consists of ground whole-carcass horsemeat along with an array of vitamins and minerals. Think of the meat you might find in a fast food taco, except made of horse. It arrives to the zoo frozen, where it gets defrosted and served to a hungry cat. The preparation completes everything from slaughtering the horse to chewing it up. All that's left for the cat is to open wide and swallow.

What happens to big cats when they're given this sort of cat food? In 1986, researchers at what was then called the San Diego Wild Animal Park (now the San Diego Zoo Safari Park) assessed the oral health and psychological well being of five captive cheetahs. The commercial diets for zoo-dwelling carnivores are nutritionally balanced, but practitioners of animal management and husbandry were starting to realize that eating is about more than nutrition. Two cheetahs were fed conventional zoo chow and three were provisioned with "either a whole, thawed bovine fetus of small to medium size or half of a larger carcass." Mmmm. Veal.

The researchers found that the cheetahs given carcasses to eat spent more time feeding and smelling their food, chewed their food more, and used their teeth to slice their food more than did those given the commercial diet. In other words, they were eating like normal cheetahs. Those given the processed product still approached their meals and ate, but they did so with less interest and were less possessive of their food. You, too, probably wouldn't mind all that much if someone stole the last few bites of your fast-food hot dog. But anyone who tried to make off with your perfectly cooked porterhouse might wind up with fork-shaped scars on their hands.

According to the researchers, the processed foods lacked a "hassle factor," which reduced the need for cheetahs to use their teeth the way evolution intended. One of the cats given that diet was actually able to "tongue" her food, no chewing required. It turns out that the so-called hassle factor is critical for maintaining good dental hygiene in big cats like cheetahs. Insufficient wear on the teeth and gums could lead to focal palatine erosion, a disorder that occurs when an underused molar chips away at the upper palate, eventually boring a hole through the bone, which can then become infected. Cheetah fangs are supposed to grow dull over time as they get used to rip into prey animals. But for those cats who eat by lapping up preprocessed horsemeat, their teeth remain sharp enough to carve holes into the bone that lines the top of their mouths.

Another study of carcass feeding in four types of big cats at three different zoos focused on the possible function of carcasses as enrichment items. Zoos go to great lengths to prevent boredom in animals by providing environmental enrichment (such as games or puzzle boxes) and social enrichment. Enrichment can decrease the frequency of repetitive, or "stereotypic," behaviors such as pacing or excessive self-grooming. It turned out that carcass feeding reduced the amount of time the cats spent on such behaviors while off-exhibit (but not while on-exhibit, for some reason).

The Toledo Zoo has experimented with letting visitors watch the zoo's carnivores dig into hunks of actual animal flesh, an event called the "Big Feed." Siberian tigers feasted on cow parts complete with hair, ears, bones, and all, as Nell Boyce reported for Radiolab in 2007. Other times visitors have watched komodo dragons nibble on a horse limb. (Zoo animals eat a lot of horse, it seems.)

Beth Stark, the zoo's curator of behavioral husbandry and research told Boyce that visitors were enthusiastic: "They'll say 'oh god, that's really gross' but then move in closer for a better view." One woman wasn't necessarily put off by the idea that the tigers were eating actual animal-shaped animals. Instead, she was disturbed by the possibility that the cow might have been alive when the tiger was first set free in its enclosure, like that scene in Jurassic Park where the goat is put out as a lure for the Tyrannosaurus.

Yet another study of Sumatran tigers and African lions at Zoo Atlanta actually tried feeding live animals—fish—to the cats. The live fish increased the frequency of feeding behaviors and increased their variety. And they decreased stereotypical behaviors by an impressive 50 percent. "Providing live food may also be more educational for the public," the researchers write, "who would get an opportunity to see carnivores engaged in the hunting and consumption of prey."

That might work for fish, but I suspect that the public might react differently if the tigers were hunting, say, cute furry floppy-eared bunnies. In fact, Stark told Boyce that visitors didn't even want to see zoo animals snacking on dead rabbits. "Around Easter, parents were worrying that their kid was thinking that the Easter bunny was being eaten."

Our moral dilemma is obviously not about meat eating per se, but about the predatory nature of carnivory. Meat is tasty, but most of us would prefer not to know too much about how chickens become nuggets. We're meat-eating, animal-loving hypocrites who are simultaneously in love with dogs and in love with bacon. We are predators, to be sure, but we sure don't like to think of ourselves as predators. Buying an eight-pack of turkey thighs or a two-pound cylinder of 80 percent lean ground pork allows us the luxury of eating meat without knowing a whole lot about the animals that wind up in our stewpots. We know their taxonomic classification (cow: Bos taurus; chicken: Gallus gallus; turkey: Meleagris gallopavo; pig: Sus scrofa), perhaps what they were fed (corn? grass? growth hormones?) and that’s about it.

It doesn't have to be that way. It would be great if everybody had to learn how to humanely slaughter and eat at least one animal in their lives, but I know that's asking a lot. It bristles with cognitive dissonance. For now, why don't we simply let animals be animals? Responsible, ethical, accredited zoos already inspire us to be better stewards of our planet and more thoughtful allies in wildlife conservation. By putting us face-to-face with a tiger tearing into the flesh of a whole cow with its face still attached, perhaps zoos can also teach us something about the animals that we shove down our own throats. Perhaps they can help us remember that we, too, are predators.

Jason G. Goldman, PhD, is a Los Angeles-based writer who covers human and animal behavior at Scientific American, BBC Future, and elsewhere. Follow him on Twitter.