Thirty-nine pregnant Sohagi ewes were divided into three equal groups to investigate the effects of an active dry yeast (Saccharomyces cerevisiae- SC, 2.44 × 10¹¹ CFU/g yeast product) on lactation curve, milk composition, blood components and growth performance of newborn lambs. Ewes in the control group were fed a basal diet without yeast supplementation (SC0), the second (SC5) and third (SC10) groups were fed the basal diet with 5 or 10 g per head/day of SC, respectively. Dry yeast supplementation increased (P < 0.05) daily milk yield, total milk yield, milk fat, protein, solids not fat contents but did not affect (P > 0.05) lactose and ash contents. Compared with the control treatment, total milk yield was improved in SC10 and SC5 by 20.3 and 14.3%, respectively. Dry yeast supplementation resulted in significant changes (P < 0.05) in the lactation curve with greater average daily milk yield noted for SC5 and SC10 over a 12-week period. Greater (P < 0.05) total protein, albumin, glucose, urea and AST concentrations were noted with dry yeast inclusion. There were no differences in globulin, cholesterol, creatinine and alanine aminotransferase concentrations. Lambs from SC10 ewes had higher (P < 0.05) birth weight than lambs from the control group. Moreover, SC10 and SC5 lambs grew faster (18.4 and 13.8%) and were heavier (16.6 and 11.9%) than lambs from control ewes. Data suggested that dry yeast supplementation improved milk yield and composition of Sohagi ewes, modified the lactation curve and enhance growth performance of lambs.