Eighteen suckling Friesian calves with average live body weight of 32.70±0.79 kg were divided into three comparable groups based on sex and birth weight. All calves were fed on a whole milk, starter and berseem hay without supplement in the control group or supplemented with 0.3 mg Se/kg DM intake as organic selenium (OSe) or nano selenium (NSe) for 2^nd and 3^rd groups. The results showed that organic-and nano selenium groups recorded significantly (P<0.05) higher digestibility of DM, OM, CP, CF, EE and NFE as well as TDN, DE and DCP compared to the control group, Plasma total protein concentration was not significantly (P>0.05) affected by selenium additives. While, albumin concentration and albumin to globulin ratio were significantly (P<0.05) decreased, however, globulin concentration in plasma of calves supplemented with OSe and NSe was significantly (P<0.05) higher than that of control group, Organic and nano selenium supplementation significantly decreased (P<0.05) the activity of AST and ALT enzymes and creatinine concentration in plasma compared to that of the control group. The concentrations of IgA and IgG in plasma were increased significantly (P<0.05) with OSe and NSe supplementation compared to the control group, The IgM concentration was comparable among all groups. The percentages of various disease incidence decreased significantly (P<0.05) in OSe and NSe supplemented groups than those of the control group, Morality rate was higher in the control group than that of OSe group, however no mortality was observed in calves of NSe group. Dry matter intake values were the same for different groups, whereas, values of TDN and DCP intake tended to increase with OSe and NSe supplemented diet than those of the control group. Birth weight was comparable among all groups. While, weaning weight, total weight gain and average daily weight gain were significantly (P<0.05) higher for OSe and NSe groups than to the control. Supplementation with OSe and NSe improved feed conversion ratio, which significant decreased (P<0.05), where the amounts of DM, TDN and DCP per one kg weigh gain were less than those of control group. Daily feed cost was comparable among all groups, where feed cost per kg gain was significantly (P<0.05) lower for OSe and NSe groups than control group. The cost price of daily weight gain and net revenue as well as economic efficiency were significantly (P<0.05) higher for OSe and NSe groups compared to those of control group.