Fifty Zaraibi goats with average body weight of 42.45±1.25 kg and aged 3-5 years after kidding were divided into five similar groups (10 in each). All goats were fed the basal diet consisted of 50% concentrate feed mixture + 31% berseem hay + 19% wheat straw. The goats in the first group (control) were fed the basal diet without supplement (G1). The goats in the first group (control) were fed the basal diet without supplement (G1). The other groups were supplemented with 0.3 mg Se/kg DM intake as inorganic selenium (sodium selenite, SS) in G2, organic selenium (yeast selenium, YS) in G3, biological organic selenium (BOSe) in G4 or biological nano-selenium (BNSe) in nano-selenium (NSe) in G5. Results showed that G5 showed significantly (P<0.05) the higher values nutrients digestibility, feeding values and feed intake followed by G4 and G3 then G2, whereas G1 had the lower values. Group 5 showed significantly (P<0.05) the highest yield of actual milk and 3.5% fat corrected milk (FCM) and the contents of fat, protein, lactose, solids not fat (SNF) and total solids (TS) followed by G4 and G3 then G2, while G1 had the lowest yield. Group 1 (control) showed significantly (P<0.05) the highest amounts of DM, TDN, CP and DCP per kg 3.5% FCM followed by G2 and G3, then G4, while G5 had the lowest values. Feed cost per 1 kg 3.5% FCM was higher in G1 followed by G2, then G3 and G4, but G5 had the lower cost. On the other side, G5 recorded significantly (P<0.05) the highest output of 3.5% FCM yield, net revenue and economic efficiency followed by G4 and G3, then G2, however G1 had the lowest values. Number of weaned kids was significantly (P<0.05) higher in G5 followed by G3 and G4 then G2, but was lower in G1. No death kids in G5 received BNSe and moreover mortality rate was the least with G3 and G4, followed by G2, but was the highest in G1 (P<0.05). Weaning weight, total weight gain and average daily gain were significantly (P<0.05) higher in G5 followed by G4 and G3, then G2, but were lower in G1. Suckled milk and the cost of suckled milk per kg weight gain were significantly (P<0.05) higher in G1 followed by G2 then G3 and G4, but G5 had the lowest values. Output of ADG, net revenue and economic efficiency were significantly (P<0.05) higher in G5 followed by G4 and G3, then G2, while G1 had the lowest values.

Keywords: Economic efficiency, Digestibility, Milk yield and composition, Selenium additive