The pork industry, together with industrial chicken production represents the worst excesses of the agro-industrial paradigm with regard to the factory farming of livestock. Swine raised by this industry spend their entire lives in confinement in huge buildings housing thousands of other animals in a totally artificial environment called a CAFO.
Agro-Industrial rearing of swine, along with chickens have been successful in producing cheap meat relative to cattle and sheep, largely because as omnivores chickens and pigs have digestive systems that are well suited to eat foods that might be partially decomposing, since in the wild, their ancestors specialized in making use of scavenged meats as well as food dug or scratched out of the ground where pathogens proliferate. These strong digestive and immune systems allow these species to be confined in large, dirty barns full of their own excrement with an "economically tolerable" level of losses whereas the he herbivores, especially ruminants who are used to eating pathogen-free grasses and greens, like cows, goats and sheep would not survive such conditions.
Highly reliant on cheap subsidized grain and the cheap energy that makes it possible, the pork industry has radically departed from traditional methods of farming not only on the scale in which each unit operates but also in the degree to which an animal is completely divorced from any semblance of its natural habitat, diet or behaviors.
The end product, while marginally cheaper than pork raised on farms, is of such low quality that the average person of a few generations ago would have not accepted it from their local butcher.
The "modern" hog is bred for a number of traits that were alien to the traditional hog breeder.
Feed conversion ratio
The amount of weight that a hog gains when fed a certain amount of feed is called the feed conversion ratio. This is very important for an industrial producer who is buying all inputs of grain feed, has high operating costs, low profit margins, and large inventories of swine, an intense focus on feed conversion ratios however, is antagonistic to a goal of pork quality. Animals which grow very quickly, without time to either mature and deposit fat or assimilate nutrients, typically have a soft, flavorless meat that is low in nutrients and pale in color. The pork industry recognizes this as a flaw which is known as PSE pork (pale, soft and exudative).
Body conformation to maximize retail cuts
Cross sectional area of loin chops