Effects of dietary FGP on serum IL-2 and IL-6 levels in layer breeder hens. a,b Values with different letters are significantly different at 5% level. CON: basal diet, FGP0.5: basal diet with fermented garlic powder 0.5 g/kg, FGP1.0: basal diet with fermented garlic powder 1.0 g/kg, FGP2.0: basal diet with fermented garlic powder 2.0 g/kg. IL-6: interleukin-6, IL-2: interleukin-2, L: linear effects, Q: quadratic effects.