Two experiments (Exp.) were conducted to determine the effects of dietary addition of five herbal plants (HP) alone or as herbal plant mixture (HPM) on in vitro gas production and ruminal fermentation patterns. In Exp. 1, five varieties of HP (garlic, eucalyptus, cinnamon, thyme, and peppermint) were added to the diet at 3 different concentrations (5, 10 and 15% of concentr ate dry matter). In Exp. 2, the HPM was used at the concentration of 2, 4 and 6%. The results show that most ruminal fermentation parameters were affected by HP and HPM. The addition of HP and HPM to the diet significantly increased total in vitro gas production (b) and the fractional rate constant of gas production (c, P<0.01). Concentrations of NH 3 (Exp. 1), CH 4 (Exp. 1 and 2), total volatile fatty acids (Exp. 1 and 2), acetate (Exp. 1), propionate (Exp. 1 and 2) and ace- tate/propionate ratio (Exp. 1) were affected by HP and HPM. Ruminal short-chain fatty acids (SCFA, P<0.01 and P<0.05 for 16 or 24 h, respectively) and organic matter degradability (OMD) were higher at 16 or 24 h of incubation with HP than control. However, dry matter degradability (DMD) and metabolizable energy (ME) of 6% HPM were lowered compared to control after 24 h (P<0.003 and P<0.04, respectively). The results point to the promising beneficial effects of HP and HPM in ruminant nutrition as rumen modi- fier to improve digestibility and nutrient utilization that may improve performance on in vivo conditions.

Keywords