A 8-weeks feeding trial was conducted to examine the effects of different levels (0, 0.5, 1 and 2%) of dietary Ferula (Ferula assafoetida) on expression of antioxidant enzymes (GSR, GPX and GSTA), immune (TNF-alpha, IL1B, IL- 8 and LYZ) and growth (GH, IGF1 and Ghrl) genes as well as cutaneous mucus