The effects of replacement of alfalfa hay with pistachio by-product (PB) at 0, 25, 50, and 75% (DM basis) on the ruminal parameters, Dry Matter Intake (DMI) of female Rayini goats, after kidding, and on the Live Weight Gain (LWG) of their kids were investigated. Five single-bearing female Rayini goats each with a single kid were employed in each level of replacement. The basal diet contained barley and alfalfa hay, the Metabolizable Energies (ME) of which were respectively 9.9 and 13.4 MJ/Kg of OM, and CP of 146 and 114 g/Kg of DM. Diets were offered to animals for ninety days. Throughout the study, DMI of female Rayini goats was measured on a daily basis, while LWG of kids assessed fortnightly. Conventional chemical composition, phenolics and their capacity to precipitate protein (PPP), In Vitro Gas Production for 24 h (IVGP), estimated Organic Matter Digestibility (OMD) and ME of the experimental diets were determined on a regular basis. Data were analyzed using the completely randomized design. As the level of PB increased in the diets, water soluble carbohydrates, neutral detergent fiber, acid detergent fiber and lignin(sa) were significantly (P<0.05) decreased, while phenolics and PPP increased (P<0.05). At 50 and 75% of PB replacement, IVGP, OMD and ME of the diets significantly (P<0.05) declined. Similarly, DMI of female Rayini goats and LWG of their kids significantly (P<0.05) declined at PB levels of 50 and 75%. Finally it can be concluded that, alfalfa hay can be substituted with BP at a level of 25% in diets of female Rayini goats following kidding, without any adverse effect on either their DMI or on their kids' LWG.