A study was conducted to evaluate the effect of slow-release urea (SRU) and/or non-structural carbohydrates (NSC) supplementation to groundnut straw (Arachis hypogaea) on digestibility and some rumen parameters in sheep and goats. A total of four male sheep (43±2.6 kg BW) and four male goats (37±1.8 kg BW) were used in a 4 × 4 Latin square design. Treatments consisted of four experimental groups; control (C) group fed basal diet, T1 fed basal diet + 10 g/day SRU, T2 fed basal diet +10 g/day SRU + molasses at 10% of ration on dry matter (DM) basis, and T3 fed basal diet +10 g/day SRU + starch at 5% of ration on DM basis. SRU and/or NSC supplementation significantly enhanced DM and organic matter (OM) digestibility, nitrogen (N) intake, urinary N, N retention, and N digestibility in sheep whereas OM digestibility, N intake, fecal and urinary N output, and N digestibility in goats. Only ammonia-N (NH3-N) levels among the rumen fluid parameters were significantly different in both sheep (P≤0.01) and goats (P≤0.05) at 2 h. In sheep and goats, rumen pH and NH3-N (P≤0.001), as well as propionate levels (P≤0.001) in goats were different at 2 h compared to 6 h. In conclusion, SRU and/or NSC supplementation improved the digestibility and weight gain, especially with corn starch under the conditions of present study.