The present invention concerns a method of culturing embryonic stem (ES) cells of avian, comprising the steps of: a) suspending ES cells originating from the blastoderm disk of fertilized un-incubated avian egg(s) in a basal culture medium supplemented with: insulin-like growth factor-1 (IGF-1) and ciliary neurotrophic factor (CNTF); and animal serum; and optionally, at least one growth factors selected in the group comprising interleukin 6 (II-6), interleukin 6 receptor (II-6R), stem cell factor (SCF), fibroblast growth factor (FGF), leukaemia inhibitory factor (LIF), interleukin 11 (II-11), oncostatin and cardiotrophin; b) seeding the suspension of ES cells obtained in step a) on a layer of feeder cells and further culturing the ES cells for at least between 2 to 10 passages; c) optionally removing at least one growth factors selected SCF, FGF, II-6, II-6R, LIF, oncostatin and cardiotrophin and II-11 from the culture medium; d) further culturing the ES cells in the medium of step c) on a layer of feeder cells.
