he current study aims to compare sugar beet leaves (SBLs) ensiled with sugar beet pulp (SBP), sugarcane molasses (SM), or rock candy juice (RCJ) using an in vitro gas production technique. Treatments in the first group included 10% SBP (control 1) and control 1 plus 5% SM or RCJ. In the second group, there were 3 treatments, including 20% SBP (control 2) and control 2 plus 10% SM or RCJ. The silages with no added soluble carbohydrate (SC) sources had significantly higher (P < 0.001) pH, buffer value index, and ammonia nitrogen values than the other treatments. However, there was no significant difference between RCJ and SM in their effect on these variables. Adding both levels of SC sources caused an increase in dry matter digestibility compared to those that only included SBL and SBP (P < 0.001). Maximal and rate of gas production from slowly fermentable fraction (a$_{2}$) were significantly greater when the substrate contained 85%, 10%, and 5% SBL, SBP, and SC sources, respectively. Using dried SBP and SC sources for the preservation of fresh SBL is recommended; however, with higher levels of SC, the silage may be at risk of spoilage, and it must be less exposed to air.