Oral immunization of sows against transmissible gastroenteritis using the T.G.E.-coronavirus strain 188-SG J.M. AYNAUD, E. BOTTREAU, A. BRUN, T.D. NGUYEN, S. BERNARD, P. BERNARDET, P. VANNIER and H. SALMON Ann. Zootech., 34 3 (1985) 371-372 DOI: 10.1051/animres:19850329