“…Moreover, the piglets have to start ingestion of artificial milk without the presence of a sow that initiates suckling episodes, in particular when piglets are young (Newberry and Wood-Gush, 1985;Worobec, 1997). Natural weaning of piglets, which can last several weeks under semi-natural conditions (Newberry and Wood-Gush, 1985;Jensen, 1986;Jensen and Recén, 1989;Stolba and WoodGush, 1989;Bøe, 1991), is a process of gradual transition from dependence on the sow's milk to growing intake of solid feed (Martin, 1984;Jensen and Recén, 1989;Petersen, 1994;Worobec, 1997;Worobec et al, 1999;Bench, 2005) when availability of milk and motherly care is slowly declining (Martin, 1984;Bøe, 1991;Bench, 2005;Widowski et al, 2008).…”