Portal absorption of 15N and amino nitrogen in the growing pig after ingestion of labelled milk, yogurt or heat-treated yogurt Didier Mpassi, Guido Rychen, Cyril Feidt, Michel Mertes, François Laurent, Irène Lenoir-Wijnkoop and Jean-Michel Antoine Reprod. Nutr. Dev., 41 2 (2001) 153-162 DOI: 10.1051/rnd:2001118