From a Mom
(On the hog farm tour I learned) That NO DRUGS can be in their systems when sent to harvest. And the incredible amount of tracking and paperwork that is done to be accountable for this. Also that keeping them inside helps prevent the need for antibiotics in the first place!
And while it may seem unnatural or unfair to keep them inside-it's actually BETTER FOR THEM INSIDE. When pigs live outside-they are exposed to the elements, which can alter how they eat and drink. Cold, shivering pigs, need more food. Hot pigs roll around in the mud, that they and their buddies also poop in, along with birds and rodents, which exposes them to diseases, which then have to be treated. Yuck! Indoors, everything is controlled for optimum piggy comfort-from temperature, food and water, ventilation, and best of all-their poop falls through slats in the floor.