The last time I checked, the soil in a pig corral was neither firm or firmish.
It’s a pig pen not a corral and FYI, a pig is actually cleaner than a chicken which will eat crap. It will NOT poop near it’s food source. Neither will a pig poop in it’s mud bath place unless it is in such a small pen that there is no other alternative. ONLY the mud bath is liquidish and there is no fecal matter there unless the dumb owner makes it so the area where the hog poops runs downhill to it. A hog’s mud bath is only mud and they do not eat the mud. They use the mud bath to cool off and to keep biting flies off of their tender skin. It does not contaminate it unless the butcherer does not wash the hide anymore than the beef is contaminated by the mud/feces that is on the beef hides and I can tell you that a cow that is being shipped to a processor whether it’s a single cow or a herd in a tractor trailer gets a “poopload” of poop all over their bodies. Also a person who has hogs does not feed his/her hogs with vegetables from the store (thrown out stuff) unless those vegetables are fresh - not sour. That’s where the “bugs” (trichinosis) get in the hog meat.