The present work investigated the effect of GABA on hematological, biochemical, antioxidant and immunological
parameters in laying hens. Sixty Lohmann Brown laying hens (32 weeks old) were randomly allotted to 3 groups (each
20) and given the medications daily for 4 weeks in drinking water. The groups were; control (without drug), GABA (40
mg/kg b.wt) and GABA (80 mg/kg b.wt). Layers were estimated to complete blood picture, Hb, differential leucocytic
count, antioxidant parameters, cholesterol, HDL, LDL, cortisol, haptoglobin, IGG, and epinephrine. There was a significant
increase in RBCs, Hb, HDL, SOD, GSH, and IGG while a decrease in MDA, cholesterol, and LDL following GABA
supplementation. In conclusion, GABA had a beneficial effect on blood picture, differential leucocytic count, antioxidant
parameters, IGG, and haptoglobin.