الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Currently, food production and processing throughout the world produce a high amount of waste and byproducts, causing adverse environmental effects and substantial costs. At the same time, there is a shortage of feeds for animal production. Hence, there is a global interest in the use of crop byproducts as non-conventional animal feeds to maximize production and reduce environmental pollution. Thus, this study investigated the potential of exogenous enzymes treatment of tomato, watermelon and date stones byproducts (TCB, WCB and DS, respectively) on gas production, rumen fermentation characteristics, and feed degradability usingin vitro gas production method. The tested multi-enzyme additive (ENZ) was manufactured from Ruminococcusflavefaciensbacteria. Four different concentrations (0, 6, 12, and 24 mg/g) of ENZ were added with the substrate (TCB, WCB and DS) inside the incubation tubes. Clover hay substrate was used as a positive control. The results of chemical analyses of TCB, WCB and DS showed that most of the nutrients are lower than those in clover hay. The untreated TCB, WCB and DS displayed a significant reduction in cumulative gas production (GP), microbial crude protein (MCP), short-chain fatty acid (SCFA), nutrient degradability, net energy (NE), and metabolizable energy (ME) contents. Still, they increased the partitioning factor value in comparison with clover hay. However, increased GP, SCFA, ME, and NE with increasing ENZ levels were observed in all crop residueswith a significant effect at the level of 24 mg/g. Also, the application of ENZ enhanced the degradation of dry matter (DM), crude protein (CP), and crude fiber (CF) compared with untreated TCB, WCB and DS. The results suggest that treatment of crop residues with ENZ, especially at 24 mg/g DM, could have the potential to improve the efficiency of feed utilization fed to ruminants, as evidenced by better gas production, in vitro DM, CF, and CP degradability.