The objective of this research was to evaluate the immune response to Salmonella Gallinarum experi-mentally infected layers fed with Guanosine 5’-monophosphate-chelated calcium and iron feed addi-tives. Hy-Line brown, 34 week-olds layers were assigned to 3 groups; Group 1: basal diet feed, Group 2 (CaFe-GMP): basal diet feed mixed with chelated calcium and iron, and Group 3 (Fe-OCHT): basal diet feed mixed with chitosan for 4 weeks. There were challenged with 1.0×108 CFU/mL of the cultured Salmonella Gallinarum (SG) by oral administration on 28th feeding days. After SG challenge, Flow cytometric profiles showed that the CD4+/CD8+ T lymphocyte activation of Group 2 was much higher than Group 1 and Group 3 (P <0.05). In addition, the levels of interleukin-2 (13.37 mg/dl) and interferon-γ (2.35 mg/dl) in Group 2 were higher than Group 1 and Group 2. Populations of Lactic acid bacteria (3.5×1010 CFU/g) from cecum was highest observed in group 2. Re-isolation of SG from cecum in group 2 (8×105 CFU/g) was lower than group 1 (1.83×1010 CFU/g). The result of this study demonstrated that CaFe-GMP feed additive may be one of the potential candidates to control salmo-nellosis and functional feeds in layers.