This study was conducted on twelve(6 male and 6 female) local calves aged 3.5-4 months and weights 50.10 ± 2.70 kg., calves were divided into 2 main groups (6 calves/group), each main group was divided into 2 subgroup according to their sex (3 males or 3 females calves/group), and fed ad libitum on iso-nitrogenous and iso-caloric rations,1st main group was fed on the first ration consist mainly of barley, soybean meal, yellow maize and wheat bran (control), while 2nd main group was fed on the second ration the same control ration, but barley and soybean meal were treated with acidic formaldehyde, in addition to feeding milk until weaning age at 8 months. Results indicated that there were no significant effect of formaldehyde treatment and calves sexes on productive performance (feed consumptions, daily and total weight gain, final body weight, and all body measurements), hematological (red & white blood counts, hemoglobin, packed cell volume and platelets counts), biochemical parameters (total protein, albumin, globulin, cholesterol, triglycerides, glucose and blood urea) and concentration of some mineral elements (calcium, phosphorus, sodium, potassium and manganese) in the blood serum. While the results indicated that of red and white blood count, packed cell volume, hemoglobin, total protein, globulin and urea were increased (P≤0.05) significantly, while the blood glucose, glycerol and triglyceride were decreased significantly (P≤0.05) by increasing the calves age.