The Omnivore's Dilemma - Michael Pollan [40]
We now understand that while at a reductive, molecular level protein may indeed be protein, at an ecological or species level, this isn’t quite true. As cannibal tribes have discovered, eating the flesh of one’s own species carries special risks of infection. Kuru, a disease bearing a striking resemblance to BSE, spread among New Guinea tribesmen who ritually ate the brains of their dead kin. Some evolutionary biologists believe that evolution selected against cannibalism as a way to avoid such infections; animals’ aversion to their own feces, and the carcasses of their species, may represent a similar strategy. Through natural selection animals have developed a set of hygiene rules, functioning much like taboos. One of the most troubling things about factory farms is how cavalierly they flout these evolutionary rules, forcing animals to overcome deeply ingrained aversions. We make them trade their instincts for antibiotics.
Though the industrial logic that made feeding cattle to cattle seem like a good idea has been thrown into doubt by mad cow disease, I was surprised to learn it hadn’t been discarded. The FDA ban on feeding ruminant protein to ruminants makes an exception for blood products and fat; my steer will probably dine on beef tallow recycled from the very slaughterhouse he’s heading to in June. (“Fat is fat,” the feedlot manager shrugged, when I raised an eyebrow.) Though Poky doesn’t do it, the rules still permit feedlots to feed nonruminant animal protein to ruminants. Feather meal and chicken litter (that is, bedding, feces, and discarded bits of feed) are accepted cattle feeds, as are chicken, fish, and pig meal. Some public health experts worry that since the bovine meat and bonemeal that cows used to eat is now being fed to chickens, pigs, and fish, infectious prions could find their way back into cattle when they’re fed the protein of the animals that have been eating them.
Before mad cow disease remarkably few people in the cattle business, let alone the general public, comprehended the strange new semicircular food chain that industrial agriculture had devised for the beef animal—and so, in turn, for the beef eater. When I mentioned to Rich Blair how surprised I’d been to learn cattle were eating cattle, he said, “To tell you the truth, it was kind of a shock to me, too.”
COMPARED TO ALL the other things we feed cattle these days, corn seems positively wholesome. And yet it too violates the biological or evolutionary logic of bovine digestion. During my day at Poky I spent a few hours with Dr. Mel Metzin, the staff veterinarian, learning more than any beef eater really should know about the gastrointestinal life of the modern cow. Dr. Mel, as he’s known at Poky, oversees a team of eight cowboys who spend their days riding the yard’s dusty streets, spotting sick animals and bringing them into Poky’s three “hospitals” for treatment. Most of the health problems that afflict feedlot cattle can be traced either directly or indirectly to their diet. “They’re made to eat forage,” Dr. Metzin explained, “and we’re making them eat grain.
“It’s not that they can’t adjust,” he continues, “and now we’re breeding cattle to do well in a feedyard.” One way to look at the breeding work going on at ranches like the Blairs’ is that the contemporary beef cow is being selected for the ability to eat large quantities of corn and efficiently convert it to protein without getting too sick. (These, after all, are precisely the genes prized in 534’s father, Gar Precision 1680.) The species is evolving, in other words, to help absorb the excess biomass coming off America’s cornfields.