Eleven experimental treatments were used by in (Origanummajorana L.) or basil (Ocimumbasilicum L. fermentation, ammonia nitrogen concentration, dry matter (DM) and cell wall contents (NDF and ADF) degradability. The basal diet consisted of a total mixed ration (TMR), the experimental treatments were used as follow: 50% CFM, 50% alfalfa hay (control), control diet plus 5, 10, 15, 20 and 25 grams of marjoram or basil leaves / kg DM for G1, G2, G3, G4, G5, G6, G7, G8, G9 and G10, respectively. No differences (p>0.05) were observed with marjoram or basil leaves supplementation in pH, DM, NDF and ADF degradability at all different levels compared with the control diet. Ammonia nitrogen and short chain fatty acid (SCFAs) concentrations reve with the control. Also, the experimental treatments recorded the lowest values (p<0.05) in total gas production (TGP), gas production per each gram of dry matter control group. It could be concluded that the addition of marjoram or basil leaves to diets had production without adverse effect on dry matter, and cell wall co