The study aimed to evaluate the potential use of dried or ensiled paulownia (Paulownia spp.) leaves as roughage source for ruminants. Paulownia tree leaves were collected from one-year-old hybrid (C-125, CAR, and TF-33 clones) trees. Dried paulownia leaves of the clones were different in dry matter (DM), crude ash (CA), crude protein (CP), ether extract (EE), crude fiber (CF), and nitrogen-free extract (NfE) and similar in neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL); however, these values (except EE and ADL) of ensiled leaves were significantly different among the clones. Mean CP, CA, and condensed tannin contents in dried leaves were 15.36, 9.21, and 1.75%, respectively; NDF, ADF, and ADL contents were 38.35, 35.49, and 12.08%, respectively. Mean total volatile fatty acids, in vitro organic matter digestibility (IVOMD), and metabolizable energy (ME) value in dried leaves were 95.26 mmol/L, 76.34%, and 10.77 MJ/kg, respectively, whereas, CO2 and CH4 production were 54.66 and 29.78 mmol/L, respectively. Buffering capacity and water-soluble carbohydrates varied among the pre-ensiled paulownia leaves, although their means were 395.66 mEq/kg DM and 86.63 g/kg DM, respectively. In ensiled leaves, the pH, lactic acid ratio, and acetic acid ratio were 4.98, 11.23, and 2.56%, respectively, and butyric acid was not detected in any of the silages. Mean values of IVOMD and ME in ensiled leaves were 72.30% and 9.93 MJ/kg, respectively. Dried paulownia leaves are a high-quality alternative forage and the ensiled form is of medium quality. Therefore, paulownia leaves could be used as an alternative roughage source for ruminants.