Urinary cortisol as an additional tool to assess the welfare of pregnant sows kept in two types of housing Françoise Pol, Valérie Courboulay, Jean-Pierre Cotte, Arnaud Martrenchar, Magali Hay and Pierre Mormède Vet. Res., 33 1 (2002) 13-22 DOI: 10.1051/vetres:2001002