Ok kids, now that you've read the "opinion", let me inject some facts. Boogada has claimed that the vegetarian lifestyle is not a healthy one. I propose that the vegetarian liefstyle is not only healthy for humans, but healthy for animals and our planet's many ecosystems. Each day, I look at the world and wonder how, as an individual, I can participate in the fight against human extinction (ie, global warming). I wonder if there is anything I can do on my own. The answer is - "go veg!" If you don't do anything else in the name of our generation or those that come after us, you can stop eating meat (or stop eating a significant amount) and become healthier and happier, all the while knowing that you are making as little impact as possible on the enviroment. Plus, for each cow you don't consume, you are saving approximately 284 gallons of oil. How? Read on...

Until mad-cow disease, remarkably few people in the cattle business, let alone the general public, comprehended the strange semicircular food chain that industrial agriculture had devised for cattle (and, in turn, for us). When I mentioned to Rich Blair that I'd been surprised to learn that cows were eating cows, he said, ''To tell the truth, it was kind of a shock to me too.'' Yet even today, ranchers don't ask many questions about feedlot menus. Not that the answers are so easy to come by. When I asked Poky's feedlot manager what exactly was in the protein supplement, he couldn't say. ''When we buy supplement, the supplier says it's 40 percent protein, but they don't specify beyond that.'' When I called the supplier, it wouldn't divulge all its ''proprietary ingredients'' but promised that animal parts weren't among them. Protein is pretty much still protein.

Compared with ground-up cow bones, corn seems positively wholesome. Yet it wreaks considerable havoc on bovine digestion. During my day at Poky, I spent an hour or two driving around the yard with Dr. Mel Metzen, the staff veterinarian. Metzen, a 1997 graduate of Kansas State's vet school, oversees a team of eight cowboys who spend their days riding the yard, spotting sick cows and bringing them in for treatment. A great many of their health problems can be traced to their diet. ''They're made to eat forage,'' Metzen said, ''and we're making them eat grain.''

Perhaps the most serious thing that can go wrong with a ruminant on corn is feedlot bloat. The rumen is always producing copious amounts of gas, which is normally expelled by belching during rumination. But when the diet contains too much starch and too little roughage, rumination all but stops, and a layer of foamy slime that can trap gas forms in the rumen. The rumen inflates like a balloon, pressing against the animal's lungs. Unless action is promptly taken to relieve the pressure (usually by forcing a hose down the animal's esophagus), the cow suffocates.

A corn diet can also give a cow acidosis. Unlike that in our own highly acidic stomachs, the normal pH of a rumen is neutral. Corn makes it unnaturally acidic, however, causing a kind of bovine heartburn, which in some cases can kill the animal but usually just makes it sick. Acidotic animals go off their feed, pant and salivate excessively, paw at their bellies and eat dirt. The condition can lead to diarrhea, ulcers, bloat, liver disease and a general weakening of the immune system that leaves the animal vulnerable to everything from pneumonia to feedlot polio.

Cows rarely live on feedlot diets for more than six months, which might be about as much as their digestive systems can tolerate. ''I don't know how long you could feed this ration before you'd see problems,'' Metzen said; another vet said that a sustained feedlot diet would eventually ''blow out their livers'' and kill them. As the acids eat away at the rumen wall, bacteria enter the bloodstream and collect in the liver. More than 13 percent of feedlot cattle are found at slaughter to have abscessed livers.

What keeps a feedlot animal healthy -- or healthy enough -- are antibiotics. Rumensin inhibits gas production in the rumen, helping to prevent bloat; tylosin reduces the incidence of liver infection. Most of the antibiotics sold in America end up in animal feed -- a practice that, it is now generally acknowledged, leads directly to the evolution of new antibiotic-resistant ''superbugs.'' In the debate over the use of antibiotics in agriculture, a distinction is usually made between clinical and nonclinical uses. Public-health advocates don't object to treating sick animals with antibiotics; they just don't want to see the drugs lose their efficacy because factory farms are feeding them to healthy animals to promote growth. But the use of antibiotics in feedlot cattle confounds this distinction. Here the drugs are plainly being used to treat sick animals, yet the animals probably wouldn't be sick if not for what we feed them.

I asked Metzen what would happen if antibiotics were banned from cattle feed. ''We just couldn't feed them as hard,'' he said. ''Or we'd have a higher death loss.'' (Less than 3 percent of cattle die on the feedlot.) The price of beef would rise, he said, since the whole system would have to slow down.

''Hell, if you gave them lots of grass and space,'' he concluded dryly, ''I wouldn't have a job.''

Before heading over to Pen 43 for my reunion with No. 534, I stopped by the shed where recent arrivals receive their hormone implants. The calves are funneled into a chute, herded along by a ranch hand wielding an electric prod, then clutched in a restrainer just long enough for another hand to inject a slow-release pellet of Revlar, a synthetic estrogen, in the back of the ear. The Blairs' pen had not yet been implanted, and I was still struggling with the decision of whether to forgo what is virtually a universal practice in the cattle industry in the United States. (It has been banned in the European Union.)

American regulators permit hormone implants on the grounds that no risk to human health has been proved, even though measurable hormone residues do turn up in the meat we eat. These contribute to the buildup of estrogenic compounds in the environment, which some scientists believe may explain falling sperm counts and premature maturation in girls. Recent studies have also found elevated levels of synthetic growth hormones in feedlot wastes; these persistent chemicals eventually wind up in the waterways downstream of feedlots, where scientists have found fish exhibiting abnormal sex characteristics.

The F.D.A. is opening an inquiry into the problem, but for now, implanting hormones in beef cattle is legal and financially irresistible: an implant costs .50 and adds between 40 and 50 pounds to the weight of a steer at slaughter, for a return of at least . That could easily make the difference between profit and loss on my investment in No. 534. Thinking like a parent, I like the idea of feeding my son hamburgers free of synthetic hormones. But thinking like a cattleman, there was really no decision to make.

I asked Rich Blair what he thought. ''I'd love to give up hormones,'' he said. ''If the consumer said, We don't want hormones, we'd stop in a second. The cattle could get along better without them. But the market signal's not there, and as long as my competitor's doing it, I've got to do it, too.''

Around lunch time, Metzen and I finally arrived at No. 534's pen. My first impression was that my steer had landed himself a decent piece of real estate. The pen is far enough from the feed mill to be fairly quiet, and it has a water view -- of what I initially thought was a reservoir, until I noticed the brown scum. The pen itself is surprisingly spacious, slightly bigger than a basketball court, with a concrete feed bunk out front and a freshwater trough in the back. I climbed over the railing and joined the 90 steers, which, en masse, retreated a few steps, then paused.

I had on the same carrot-colored sweater I'd worn to the ranch in South Dakota, hoping to jog my steer's memory. Way off in the back, I spotted him -- those three white blazes. As I gingerly stepped toward him, the quietly shuffling mass of black cowhide between us parted, and there No. 534 and I stood, staring dumbly at each other. Glint of recognition? None whatsoever. I told myself not to take it personally. No. 534 had been bred for his marbling, after all, not his intellect.

I don't know enough about the emotional life of cows to say with any confidence if No. 534 was miserable, bored or melancholy, but I would not say he looked happy. I noticed that his eyes looked a little bloodshot. Some animals are irritated by the fecal dust that floats in the feedlot air; maybe that explained the sullen gaze with which he fixed me. Unhappy or not, though, No. 534 had clearly been eating well. My animal had put on a couple hundred pounds since we'd last met, and he looked it: thicker across the shoulders and round as a barrel through the middle. He carried himself more like a steer now than a calf, even though he was still less than a year old. Metzen complimented me on his size and conformation. ''That's a handsome looking beef you've got there.'' (Aw, shucks.)

Staring at No. 534, I could picture the white lines of the butcher's chart dissecting his black hide: rump roast, flank steak, standing rib, brisket. One way of looking at No. 534 -- the industrial way -- was as an efficient machine for turning feed corn into beef. Every day between now and his slaughter date in June, No. 534 will convert 32 pounds of feed (25 of them corn) into another three and a half pounds of flesh. Poky is indeed a factory, transforming cheap raw materials into a less-cheap finished product, as fast as bovinely possible.

Yet the factory metaphor obscures as much as it reveals about the creature that stood before me. For this steer was not a machine in a factory but an animal in a web of relationships that link him to certain other animals, plants and microbes, as well as to the earth. And one of those other animals is us. The unnaturally rich diet of corn that has compromised No. 534's health is fattening his flesh in a way that in turn may compromise the health of the humans who will eat him. The antibiotics he's consuming with his corn were at that very moment selecting, in his gut and wherever else in the environment they wind up, for bacteria that could someday infect us and resist the drugs we depend on. We inhabit the same microbial ecosystem as the animals we eat, and whatever happens to it also happens to us.

I thought about the deep pile of manure that No. 534 and I were standing in. 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. One particularly lethal bug most probably resided in the manure beneath my feet. Escherichia coli 0157 is a relatively new strain of a common intestinal bacteria (it was first isolated in the 1980's) that is common in feedlot cattle, more than half of whom carry it in their guts. Ingesting as few as 10 of these microbes can cause a fatal infection.

Most of the microbes that reside in the gut of a cow and find their way into our food get killed off by the acids in our stomachs, since they originally adapted to live in a neutral-pH environment. But the digestive tract of the modern feedlot cow is closer in acidity to our own, and in this new, manmade environment acid-resistant strains of E. coli have developed that can survive our stomach acids -- and go on to kill us. By acidifying a cow's gut with corn, we have broken down one of our food chain's barriers to infection. Yet this process can be reversed: James Russell, a U.S.D.A. microbiologist, has discovered that switching a cow's diet from corn to hay in the final days before slaughter reduces the population of E. coli 0157 in its manure by as much as 70 percent. Such a change, however, is considered wildly impractical by the cattle industry.

So much comes back to corn, this cheap feed that turns out in so many ways to be not cheap at all. While I stood in No. 534's pen, a dump truck pulled up alongside the feed bunk and released a golden stream of feed. The animals stepped up to the bunk for their lunch. The .60 a day I'm paying for three giant meals is a bargain only by the narrowest of calculations. It doesn't take into account, for example, the cost to the public health of antibiotic resistance or food poisoning by E. coli or all the environmental costs associated with industrial corn.

For if you follow the corn from this bunk back to the fields where it grows, you will find an 80-million-acre monoculture that consumes more chemical herbicide and fertilizer than any other crop. Keep going and you can trace the nitrogen runoff from that crop all the way down the Mississippi into the Gulf of Mexico, where it has created (if that is the right word) a 12,000-square-mile ''dead zone.''

But you can go farther still, and follow the fertilizer needed to grow that corn all the way to the oil fields of the Persian Gulf. No. 534 started life as part of a food chain that derived all its energy from the sun; now that corn constitutes such an important link in his food chain, he is the product of an industrial system powered by fossil fuel. (And in turn, defended by the military -- another uncounted cost of ''cheap'' food.) I asked David Pimentel, a Cornell ecologist who specializes in agriculture and energy, if it might be possible to calculate precisely how much oil it will take to grow my steer to slaughter weight. Assuming No. 534 continues to eat 25 pounds of corn a day and reaches a weight of 1,250 pounds, he will have consumed in his lifetime roughly 284 gallons of oil. We have succeeded in industrializing the beef calf, transforming what was once a solar-powered ruminant into the very last thing we need: another fossil-fuel machine.