Material and methods
2.1. Source and composition of REE-citrate
The product Lancer1 500 used in this study consisted of 50% wheat starch and 50% lanthanoide, whereby the lanthanoide (REE-citrate) itself consisted of 25.3%
(growing period) and 38.7% (fattening period) rare earth elements and 74.7% and
61.3% citrate, respectively. The REE-citrate was a mixture containing organic citrate compounds of 57.9% cerium, 34.0% lanthanum, 6.5% praseodymium and 1.6% of other rare earth elements (Lancer1500, Zehentmayer AG Berg, Switzerland). In Switzerland, this product is permitted as a ‘‘lanthanoide’’ feed additive in compound feed of piglets and fattening pigs.