The study aimed to investigate if plant based high energy mash diets supplemented with NaHCO3, L-arginine + vitamin-C and vegetable oils were effective against tachycardia and polycythemia in the commercial broiler chicken. Total 256Ross-308 day old male broiler chicks were randomly distributed into eight dietary treatment groups in a three way 23 factorial arrangements (Three factors, i.e., NaHCO3, L-arginine + vitamin-C and vegetable oil each with two levels, e.g., 0 and 0.1% for NaHCO3 and L-arginine + vitamin-C; 3 and 4% of vegetable oil supplemented with basal diet). Iso-caloric and iso-nitrogenous diets were formulated and supplied ad libitum. The average daily feed intake (ADFI), average daily gain (ADG), feed efficiency (FE), carcass characteristics, cardio-pulmonary morphometry, total protein (TP), hemoglobin (Hb), triiodothyronine (T3), incidence of tachycardia and polycythemia were examined up to 35 d. Supplementation of NaHCO3decreased (p<0.001) the ADFI at 1-14 d, 15-35 d, 1-35 d, improved (p<0.01) the FE at 1-14 d and increased (p<0.05) the serum TP. Dietary L-arginine + vitamin-C decreased (p<0.01) the heart rate without affecting the performance parameters, carcass characteristics and hemato-biochemical indices. Supplementation of vegetable oil decreased (p<0.01) the ADFI at 1-14d, 15-35 d, 1-35 d, increased (p<0.01) the ADG at 1-14d, improved (p<0.001) the FE at 1-14 d and increased (p<0.05) the heart rate, Hb and PCV. Further, NaHCO3, L-arginine + vitamin-C and vegetable oil synergistically interacted to decrease the left and right ventricular weight, RV:TV and increased the T3 without affecting overall performance, carcass characteristics and hemato-biochemical indices. It was concluded that, plant based high energy mash diets are not susceptible to tachycardia and polycythemia. Addition of NaHCO3, L-arginine + vitamin-C ameliorate the propensity of tachycardia and polycythemia without deteriorating performance, carcass characteristics and hemato-biochemical indices of the commercial broiler birds in a dose dependent manner.