Twelve local Zaraiby goats with average live body weight of 10.71±0.23 kg (5-6 months). Animals were divided into three comparable groups. Goats in first group were fed without supplement (control group) or sup-plemented with 25% ordinary cobalt and 25% nanocobalt from cobalt requirements (NRC, 1985). The results showed that no significant difference (P>0.05) among experimental groups for DMI and CPI values. However, there was a highest significant difference (P<0.05) in average daily gain, total gain, and feed efficiency (kg gain/ kg DMI) for nanoco-balt group. Nutrients digestibility values as DM, CP, CF, NFC, ADF, NDF, cellulose and hemicellulose in addition to percentage of TDN in nanocobalt treatment were higher sig-nificantly than those others groups. But the ra-tio of nitrogen balance in goats' diet with nano-cobalt group was less than that using ordinary cobalt and control group. While the DE (Mcal/Kg DMI) ratio was no significant differ-ences observed among groups. Rumen pH and TVFA’s values after 3 and 6 hours of feeding, the control and the ordinary cobalt groups in-creased (P<0.05) more than the nanocobalt group. After 3hrs, adding nanocobalt has lower significant values for NH3-N than those others. Where, the control group recorded the lowest value. No significant (P>0.05) differences were observed at 0, 3and 6 hrs. after feeding for all blood parameters. There was a slight in-crease for most of body measurements with nanocobalt supplement. It could be concluded that adding nanocobalt for goats' rations en-hanced growth performance, digestibility coef-ficients, rumen parameters and slightly body measurements without any diverse effect on animals' health.