Nine Rahmany rams with an average body weight of 70.35 ± 1.7 kg and 3 years of age were used at El-Serw Experimental Research Station to study the effect of silage and hay of potato by-product (vine and greenish spots small and damage tubers) on feeding values and semen characteristics. Rams were randomly divided into three treatment groups, assigned to three trials with three experimental rations.  The first trial was to evaluate digestibility and nutritivevalues; the second trial to estimate blood parameters and the third trial was carried out to evaluate semen characteristics.  The experimental diets were given according to NRC (1990), first group fed 50% concentrate feed mixture (CFM) + 50% berseem hay as a control (CBH), second group fed 50% CFM + 50% potato by-products + 5% molasses + 3% urea as silage (PB-PS) and third group fed 50% CFM + 50% potato by- products hay (PB-PH).  The experiment lasted for 12 weeks .The obtained results showed that digestibility of crude protein and ether extract of PB-PH decreased than of PB-PS and CBH groups. Also, DCP significantly decreased in PB-PH  (P < 0.05) in comparison to the other treatments.  Results explained that blood parameters for group fed PB-PH were significantly (P < 0.05) decreased (RBC, total protein, albumin, globulin and cholesterol).  However, hematocrit, AST, ALT, urea, creatinine and bilirubin values of PB-PH group were significantly (P < 0.05) increased compared to PB-PS and CBH groups.  Ration containing CBH and PB-PS recorded higher (P < 0.05) semen characteristics than PB-PH ration. Ejaculate volume was 1.65 ± 0.07, 1.63 ± 0.13 and 1.48 ± 0.17 ml for ram groups fed CBH, PB-PS and PB-PH, respectively .The percentage of sperm motility was lower for PB-PH group (80.5 ± 3.86) than both CBH (87.39 ± 1.37) and PB-PS (86.11 ± 1.43).  Rations containing CBH and PB-PS led to a significant (P < 0.05) increase in live spermatozoa compared with PB-PH ration. Feeding CBH and PB-PS rations accompanied with higher sperm cell concentration than for those fed PB-PH ration.  The sperm cell concentration was 3.73 ± 0.14, 3.66 ± 0.15 and 2.86 ± 0.90 x 10⁹/ml for rams were fed CBH, PB-PS and PB-PH, respectively.  The feed cost was decrease with PB-PS and PB-PH compared with the control one. Therefore, the present study found that potato by-products silage could improve nutrition and semen characteristics in rams and reduce feed cost.