During summer season average maximum temperature was observed 40.80c at 2 pm and THI 85. The physiological responses (RT, RR, PR and ST) increased significantly (p<0.01) at 2 pm as compared to respective values at 2 am. Rectal temperature, respiration rate and pulse rate were positively correlated with dry bulb temperature in both the species. The circadian rhythmic variations in core temperature during summer were 1.00C and 1.40C, respectively for adult and growing KF cattle. The respective values for Murrah buffaloes were 0.90C and 1.20C. During winter the rhythmic variations in KF adults and growing cattle were 0.60C and 0.90C, respectively whereas during spring season the respective values were 0.80C & 0.90C. In Murrah adult and growing buffaloes the rhythmic variations during winter were 1.10C & 0.70C, respectively. The respective values during spring season were 0.70C & 0.80C. Skin temperature significantly differed between season and species (P<0.01) in Karan Fries cattle and Murrah buffaloes. A diurnal variation in skin temperature during summer in both adult and growing cattle was 9 -100C whereas during spring season the variation in skin temperature was 5 � 70C. These changes in skin temperature were positively correlated with changes in ambient temperature during different intervals of time, however, the maximum gradient of change was observed at 2 pm and minimum at 2 am. During spring season the heat load in Murrah adult was observed maximum 79 at 2 pm and minimum 63 at 2 am and in growing was 79 at 2 pm and minimum 66 at 2 am. During summer season the heat load in growing Murrah buffaloes was observed maximum 90 than adult 88 at 2 pm and the values at 2 am were 73 and 72, respectively. During spring season the heat load on adult and growing Karan Fries cattle were similar and during summer season maximum heat load was found in adult Karan Fries cattle 93 than growing Karan Fries cattle 92 at 2 pm and at 2 am. Heat load observed in Karan Fries adult 76 and growing was 74. Heat load during summer season was (P<0.05) significantly differed between season and species 1293779969.php