#feedlots

The unnaturally rich diet of corn that undermines a steer's health fattens his flesh in a way that undermines the health of the humans who will eat it. The antibiotics these animals consume with their corn at this very moment are selecting, in their gut and wherever else in the environment they end up, for new strains of resistant bacteria that will someday infect us and withstand the drugs we depend on to treat that infection. We inhabit the same microbial ecosystem as the animals we eat, and whatever happens in it also happens to us. Then there's the deep pile of manure on which I stand, in which 534 sleeps. We don't know much about the hormones in it—where they will end up, or what they might do once they get there—but we do know something about the bacteria, which can find their way from the manure on the ground to his hide and from there into our hamburgers. The speed at which these animals will be slaughtered and processed—four hundred an hour at the plant where 534 will go— means that sooner or later some of the manure caked on these hides gets into the meat we eat. One of the bacteria that almost certainly resides in the manure I'm standing in is particularly lethal to humans. Escherichia coli 0157:H7 is a relatively new strain of the common intestinal bacteria (no one had seen it before 1980) that thrives in feedlot cattle, 40 percent of which carry it in their gut. Ingesting as few as ten of these microbes can cause a fatal infection; they produce a toxin that destroys human kidneys. Most of the microbes that reside in the gut of a cow and find their way into our food get killed off by the strong acids in our stomachs, since they evolved to live in the neutral pH environment of the rumen. But the rumen of a corn-fed feedlot steer is nearly as acidic as our own stomachs, and in this new, man-made environment new acid-resistant strains of E. coli, of which 0157:H7 is one, have evolved—yet another creature recruited by nature to absorb the excess biomass coming off the Farm Belt. The problem with these bugs is that they can shake off the acid bath in our stomachs—and then go on to kill us. By acidifying the rumen with corn we've broken down one of our food chain's most important barriers to infection. Yet another solution turned into a problem. We've recently discovered that this process of acidification can be reversed, and that doing so can greatly diminish the threat from E. coli 0157:H7. Jim Russell, a USDA microbiologist on the faculty at Cornell, has found that switching a cow's diet from corn to grass or hay for a few days prior to slaughter reduces the population of E. coli 015 7:H7 in the animal's gut by as much as 80 percent. But such a solution (Grass?!) is considered wildly impractical by the cattle industry and (therefore) by the USDA. Their preferred solution for dealing with bacterial contamination is irradiation—essentially, to try to sterilize the manure getting into the meat.