A scientific study found that pigs living in a seminatural environment spent 52 percent of daylight hours rooting and grazing and another 23 percent walking around investigating the environment. They are driven to explore their world. (Sadly, 95% of all pigs in the Netherlands are raised in conventional systems, where, at the very best, the only type of exploration they are offered is to inspect a ball at the end of a chain).
Grandin, Temple and Catherine Johnson. Animals make us Human. Houghton Mifflin Harcourt, Boston 2009: p. 173.