Smithfield's pigs live by the hundreds or thousands in warehouse-like barns, in rows of wall-to-wall pens. Sows are artificially inseminated and fed and delivered of their piglets in cages so small they cannot turn around. Forty fully grown 250-pound male hogs often occupy a pen the size of a tiny apartment. They trample each other to death. There is no sunlight, straw, fresh air or earth. The floors are slatted to allow excrement to fall into a catchment pit under the pens, but many things besides excrement can wind up in the pits: afterbirths, piglets accidentally crushed by their mothers, old batteries, broken bottles of insecticide, antibiotic syringes, stillborn pigs -- anything small enough to fit through the foot-wide pipes that drain the pits. The pipes remain closed until enough sewage accumulates in the pits to create good expulsion pressure; then the pipes are opened and everything bursts out into a large holding pond. The temperature inside hog houses is often hotter than ninety degrees. The air, saturated almost to the point of precipitation with gases from shit and chemicals, can be lethal to the pigs. Enormous exhaust fans run twenty-four hours a day. The ventilation systems function like the ventilators of terminal patients: If they break down for any length of time, pigs start dying. From Smithfield's point of view, the problem with this lifestyle is immunological. Taken together, the immobility, poisonous air and terror of confinement badly damage the pigs' immune systems. They become susceptible to infection, and in such dense quarters microbes or parasites or fungi, once established in one pig, will rush spritelike through the whole population. Accordingly, factory pigs are infused with a huge range of antibiotics and vaccines, and are doused with insecticides. Without these compounds -- oxytetracycline, draxxin, ceftiofur, tiamulin -- diseases would likely kill them. Thus factory-farm pigs remain in a state of dying until they're slaughtered. When a pig nearly ready to be slaughtered grows ill, workers sometimes shoot it up with as many drugs as necessary to get it to the slaughterhouse under its own power. As long as the pig remains ambulatory, it can be legally killed and sold as meat.