effect of essential oils of zataria multiflora, eucalyptus globolus and their combination on fermentation parameters using merghoz goat rumen liquor

In this experiment, different doses of zataria multiflora (zm) and eucalyptus globolus (eg) essential oils (eos) (0, 100, 250, 500, 750 and 1000 μg/ml) and a mixture of them were added to alfalfa hay incubated with buffered rumen liquor of merghoz goat to assess in vitro gas production, rumen fermentation and pro-tozoa population. in all treatments the asymptotic gas volume (b) and the rate constant (c) were decreased while the lag phase was increased. there were no effects of zm and eg on ph, but in high doses of ze ph was higher than that of control (p<0.001). the ammonia-n concentration was decreased due to addition of combination of eos (p<0.01) and volatile fatty acid concentration was reduced (p<0.01) following incorpo-ration of eos. gas production and organic matter digestibility were decreased (p<0.01) 24 h after incuba-tion, whereas the partitioning factor was increased. metabolizable energy was decreased, (p<0.05). by in-clusion of eos, total protozoa population and individual genera reduced (p<0.001). the results revealed that eos of zm and eg could be potentially used to modulate rumen fermentation, but using them at high level doses have anti-protozoal effects.