“…Stereotypic behavior can be defined as "repetitive, invariant behavior patterns with no obvious goal or function" (Mason, 1991(Mason, , p. 1015. Common stereotypic behavioral patterns in domestic swine are often based on oral-nasal activity, such as bar-biting, sham-chewing, drinker-pressing, head-weaving, nose-rubbing, and tongue-rolling (Broom, 1986;Robert, Rushen, & Farmer, 1997;Stolba, Baker, & Wood-Gush, 1983;Vieuille-Thomas, Le Pape, & Signoret, 1995). The addition of substrates such as straw, peat and mushroom compost to swine housing has been shown to decrease common stereotypic behaviors and aggression toward pen mates (Arey, 1993;Beattie et al, 1995;Fraser, Phillips, Thompson, & Tennessen, 1991;Kelly, Bruce, English, Fowler, & Edwards, 2000;Sneddon, Beattie, Walker, & Weatherup, 2001;Wood-Gush & Beilharz, 1983).…”