Ruminants are major contributorsof methane (CH4) production. Serious global efforts are required to reduce CH4 produced through their digestive tract, which isgenerally termed as enteric methane production (e.m.p). Feeding diets containing nitrates and/or sulphates could be used to reduce e.m.p. The study was conducted to evaluate the influence of varying levels of sodium nitrate (SN) with or without sulphur (S) on the growth performance and e.m.p in Lohi sheep and Teddy goats in a 2×3×2 factorial arrangement under Randomized Complete Block Design. In the experiment, 48 male animals (24 Lohi sheep and 24 Teddy goats of approximately nine months of age), were randomly divided into 12 groups, 4 animals in each group. Six iso-nitogenous and iso-caloric diets were formulated. The control diet SN0-S0 contained neither SN nor S. Whereas SN0-S4, SN2.5-S0, SN2.5-S4, SN5-S0 and SN5-S4 diets had 0% SN and 0.4% S, 2.5% SN and 0% S, 2.5% SN and 0.4% S, 5% SN and 0% S and 5% SN and 0.4% S, respectively. Nonprotein nitrogen was same across all diets. The Gases were measured by using infra-red biogas analyzer. The nutrient intake and digestibility in both sheep and goats were similar (P> 0.05) across all diets. The animals fed diet containing 5% SN with 0.4% S showed better nitrogen balance. The enteric CH4 was 19.6% reduced (P<0.05) in sheep and 18.2% in goats fed diet containing 5% SN and 0.4% S compared to those fed control diet. Daily live weight gain of both sheep and goats fed diet containing 5% SN and 0.4% S was 143 and 59 g/day, respectively. The best feed conversion values (P<0.05) were observed in sheep fed both SN2.5-S4 and SN5-S4 diets. However, best feed conversion ratio was observed in goats fed SN5-S0 and SN5-S4 diets. Both in sheep and goats non-significant differences (P> 0.05) were observed in blood metabolites including blood urea nitrogen, glucose and Creatinine. Similar trend (P> 0.05) was observed in hematology. None of the animal showed any kind of abnormal behaviour or signs of illness during the whole experimental period. It can be concluded that supplementation of forage-based diet with SN in combination with sulphur is not only effective to reduce the e.m.p but also improves the weight gain in fattening sheep and goats.