Pigs investigate their surroundings by performing digging, sniffing, biting and chewing movements. Therefore, a lack of investigation and manipulation materials can adversely affect the behavior of the pigs. Some weahners and finishers develop hale biting behavior that is related to their current motivational state. 

Therefore, the current Danish legislation set up the minimum standards for the protection of pigs (pig farming). According to the current rules, “pigs must have permanent access to a sufficient amount of materials that they can properly investigate and red in.”