OBJECTIVE: This work was to investigate the effect of using Azolla (Azolla microphylla) leaf meal and phytonutrient powder on rumen fermentation efficiency and nutrient degradability using in vitro technique. METHODS: All respective treatments were imposed in a 2×4×2 Factorial arrangements according to a completely randomized design. The first factor was two ratios of roughage to concentrate (R:C at 60:40, and 40:60), the second factor was Azolla (Azolla microphylla) powder (AMP) supplementation levels (0%, 3%, 6%, and 9% of the total substrate) and the third factor was turmeric (Curcuma longa) powder (TUP) supplementation levels (0% and 2% of the total substrate). RESULTS: Cumulative gas production at 96 h, was affected by R:C and numerically increased by AMP and TUP supplementation (p<
0.05). Gas production kinetics increased with the increasing ratio of concentrate and AMP supplementation whereas TUP supplement reduced gas production. In vitro dry matter degradability was remarkably increased (p<
0.05) by the R:C ratio, AMP and TUP supplementation. However, increasing R:C ratio, AMP and TUP supplementation resulted in the concentration of propionate (C3) significantly increasing (p<
0.05). Acetate (C2), C2:C3 ratio, and protozoal population were improved (p<
0.05), while the methane production decreased. CONCLUSION: Under this study, the results were obtained under the supplementation level of 9% AMP and 2% TUP of total substrate, hence, the combined use is potentially beneficial. These results revealed a potential use of AMP and TUP as a supplement to improve rumen fermentation for ruminant feeding. Nevertheless, in vivo feeding trials should be further investigated using AMP and TUP as a source of protein and phytonutrient.