This study aimed to evaluate the effect of adding 10, 20, and 30% Sesbania hay (SH) to diet at expense of berseem hay (BH) on productive and reproductive performance of Ossimi ewes post-lambing. Thirty-six ewes weighted 38.31 ± 0.91 kg 30d before lambing were used in a randomized complete block design with four experimental rations. Rations were formulated as follow: R₁ (60% concentrate feed mixture (CFM) and 40% BH) and served as control, R₂ (60% CFM + 30% BH + 10% SH), R₃ (60% CFM + 20% BH + 20% SH) and R₄ (60% CFM + 10% BH + 30% SH). Results demonstrated that feed conversion was somewhat lower with SH-containing rations. The treatment rations significantly increased blood urea-N concentrations. In addition, serum protein, cholesterol, ALT, and glucose concentrations were significantly (P<0.05) increased with R₄ compared to R₁. Treatments R₃ and R₄ led to a significant (P<0.05) decrease in milk yield. Replacing BH with SH by 30% resulted in a decrease (P < 0.05) in milk fat compared to other groups, while milk protein followed the opposite trend. First estrus post-lambing and estrus duration for ewes fed on SH was longer than for control. While SH supplemented rations decreased both P4 and E2 concentrations (P<0.05) compared to control. The economic efficiency was noticeably higher with SH-supplemented rations. Accordingly, it could be concluded that substitutions up to 30% of BH by SH have not left any adverse effects on ewes' performance, and metabolic parameters.