This study was carried out to investigate the effect of large particles (zinc Zn or selenium SE ) or nano-Zn and nano-Se particles as feed supplement in lambs rations on feed intake, degradability, growth performance and some blood parameters. Twenty five growing  lambs aging about 5-6 months with average body weight of  24.5kg, were used. Lambs were divided into five similar  groups and fed randomly on one of the following rations. The first group received the basal ration, composed of concentrate feed mixture (CFM) to cover 50% of protein and energy allowances recommended by NRC (1989) and clover hay (CH) without feed additives which served as the control group (R1). The other tested groups were randomly fed the control ration supplemented with 10 mg large particles zinc (L-Zn), 0.04 mg large particles selenium (L-Se), 5 mg nano particles zinc (N-Zn)  and 0.02 mg nano particles selenium (N-Se) / kg CFM for rations R2,R3, R4  and R5, respectively. Two canulated sheep were used to measure in sacco disappearance of DM, OM  and CP of tested rations.   Results showed that N-Zn & N-Se particles groups improved DM, OM and CP degradability compared with control group.  But there were no significant differences among large particles groups and control group.  Ration contained N-Zn had a significant effect on DM intake, but there were no significant differences among the large particles  zinc (L-Zn) or selenium (L-Se) groups and control group among DMI.  On the meantime, results showed that R4 & R5 groups increased (P<0.05) average daily gain and total weight gain compared to the control group. Also, feed conversation as DMI/ kg gain for R4 & R5 groups were improved by 16.93 and 18.25%, as compared with control group.  Feed cost /kg gain was decreased for R4 and R5 groups as compared with control group.  Serum total protein and albumin for R4 was increased compared with control group.  While no significant differences between control group and other groups were found among AST and  ALT values. In conclusion, large size particles of  Zn  or Se  could be replaced  with smaller amount of nano particles Zn  or Se  without  any   side effects on the animal performance.