The current study was conducted to evaluate the component composition, anti-nutritional factors, in vitro gas production (GP) and methane (CH4) production profiles of fruit by-products (pineapple pulp, mango seed kernels, banana and papaya peel, Moringa stenopetala and Moringa oleifera seeds) and leaves of root crops (sweet potato [Ipomoea batatas], cassava [Manihot esculenta], yam [Dioscorea abyssinica], enset [Ensete ventricosum] and samma [Urtica simensis]). Root crop leaves had high crude protein (CP) ranging from 211 to 318 g/kg dry matter (DM) in yam and samma, respectively. M. stenopetala seeds contained the highest CP (450 g/kg DM). Samma leaves were rich in calcium (58.6 g/kg DM) and iron (1186 mg/kg DM). Leaves of root crops had similar concentrations of essential amino acids with appreciable values. Total phenols were highest in mango seed kernels (158 g/kg DM). The asymptotic GP at 96 h incubation of pineapple pulp, papaya and banana peel was 397, 358 and 279 ml/g DM, respectively, and differed significantly from each other. Sweet potato and yam leaves produced 238 and 225 ml/g DM GP, respectively, being significantly higher than those of other root crops. CH4 production was significantly lowest in Moringa seeds, mango seed kernels and sweet potato leaves. In conclusion, fruit by-products have the potential as energy sources and root crop leaves as protein supplements for ruminant and non-ruminant animals. Moringa seeds, mango seed kernels and sweet potato leaves were identified as potential candidates in mitigating CH4 emissions in tropical livestock with animal-based experiments recommended to validate the in vitro findings.