Twenty one buffalo heifers of one year age and similar body weight were divided into three groups, A, B and C. Three total mixed rations (TMR) with different energy levels were randomly allotted to these groups. Ration B contained 100%NRC energy recommendations, (control) while ration A and ration C contained 80% and 120% energy. These rations were fed for a period of 18 months. Blood sampling was done at monthly intervals to determine the hematological indices and serum electrolytes. Data were analyzed using mixed model least squares and maximum likelihood computer program (ISMLMW). Energy levels had significant effect (P<0.05) on blood coagulation time. During winter, there was marked increase in blood coagulation time, (6.75 minutes) while, it was significantly decreased during summer. These values were higher (P<0.05) during post pubertal age. A significant increase in erythrocyte count was found during spring. The erythrocyte count during young age was lower (P<0.05) as compared to post pubertal stage. Energy levels had no effect on total leukocyte count. Erythrocyte Sedimentation Rate (ESR) values were significantly (P<0.01) affected by energy levels with maximum value in ration B. Season and age also had effect on ESR. PCV values were highest (P<0.05) on medium energy ration and lower (P<0.01) during younger age. Higher levels (P<0.05) of hemoglobin were found in group of buffaloes fed high energy ration. Season had no effect whereas, concentration was lower at pre-pubertal age. A significant increase in sodium concentration was recorded during post pubertal age as compared to pre- pubertal age (P<0.01). Potassium ion concentration was significantly affected by different energy levels in feed (P<0.05) with highest value in ration C. Season and age had also significant effect on potassiumconcentration (P<0.01). The chloride concentration was significantly (P<0.01) affected by dietary energy levels and season. Highest values of calcium concentration were recorded during spring and post pubertal stage as compared to pre pubertal stage (P<0.05).