Asian Journal of Animal Sciences1819-1878xxxx-xxxxxAsian Network for Scientific Information10.3923/ajas.2009.1.12SoltanMosaad Abd El-Khalek ShewitaRamadan Saeed Al-SultanSaad I. 1200931Sixty lactating Holstein dairy cows were assigned to investigate the effect of Essential Oil Mixture (EOM) addition (mixture of eucalyptus oil 7%; menthol crystal 6.6% and mint oil 2.0%) on digestion, rumen fermentation, rumen microbial populations, milk production and milk composition. Cows were allotted into four groups (15 animals per each) and received EOM at (0, 16, 32 or 48 mg L-1 of drinking water) for successive eight weeks. Addition of EOM at 16 mg L-1 drinking water increased body weight gain, decreased feed intake and improved milk-to-feed ratio by about 7.4, 3.8 and 4.4%, respectively, across the whole experimental period when compared with the control, while moderate and higher addition levels of EOM (32 and 48 mg L-1 water) had variable results and not confirm the stability of animal performance. Addition of EOM had no significant effect on ruminal pH and ruminal fluid ammonia concentration and increased total Volatile Fatty Acid (VFA) by about 2.5, 2.9 and 0.7, respectively when compared with control. On the other hand, EOM (16 or 32 mg L-1 water) decreased molar proportion of acetate, whereas that of propionate increased compared with control and with the higher addition level (48 mg L-1) of EOM receiving cows. Total viable bacteria, cellulolytic bacteria and protozoa counts were not changed with EOM supplementation. However, protozoa counts numerically decreased with EOM addition. Apparent digestibility of dry matter, organic matter and crude protein were slightly improved (p>0.05) with EOM supplementation compared with control. Addition of EOM (16 mg L-1) improved (p>0.05) milk production across the whole experimental period, while the higher levels decreased (p>0.05) milk production when compared with control. Lower milk fat and higher milk protein was observed for cows received EOM than control and the milk protein showed the opposite direction. Results from this study suggest that EOM addition at 16 mg L-1 water slightly improved milk-to-feed ratio and productive performance and had limited effect on digestion and ruminal fermentation characteristics of dairy cows while, the higher dose may have negative effect of the productivity and ruminal fermentation of dairy cows.]]>AOAC,199015th Edn.,pp: 200-210pp: 200-210Benchaar, C., H.V. Petit, R. Berthiaume, D.R. Ouellet and J. Chi-Quette,200383637637Benchaar, C., H.V. Petit, R. Berthiaume, T.D. Whyte and P.Y. Chouinaed,20068943524364Benchaar, C., H.V. Petit, R. Berthiaume, D.R. Ouellet, J. Chiquette and P.V. Chouinard,200790886897Benchaar, C., J.L. Duynisveld and E. Charmley,2006869196Bligh, E.G. and W.J. Dyer,19591959Busquet, M., S. Calsamiglia, A. Ferret and C. Kamel,2006in vitro rumen microbial fermentation.]]>89761771Busquet, M., S. Calsamiglia, A. Ferret and C. Kamel,2005123-124597613Cardozo, P.W., S. Calsamiglia, A. Ferret and C. Kamel,20068428012808Cardozo, P.W., S. Calsamiglia, A. Ferret and C. Kamel,20048232303236Castillejos, L., S. Calsamiglia and A. Ferret,2006in vitro systems.]]>8926492658Castillejos, L., S. Calsamiglia, A. Ferrer and L. Losa,20051192941Dorman, H.J.D. and S.G. Deans,200088308316Evans, J.D. and S.A. Martin,200041336340Fraser, G.R., A.V. Chaves, Y. Wang, T.A. McAllister, K.A. Beauchemin and C. Benchaar,20079023152328Greathead, H.,200362279290Grubb, J.A. and B.A. Dehority,197631262267Hanson, S.W.F. and J. Olly,19631963Hristov, A.N., T.A. McAllister, F.H. van Herk, K.J. Cheng, C.J. Newbold and P.R. Cheeke,1999Yucca schidigera on ruminal fermentation and nutrient digestion in heifers.]]>7725542563Hummelbrunner, L.A. and M.B. Isman, 2001Spodoptera litura (Lep., Noctuidae). ]]>49715720ISO,1998Koch, A.L.,19941994Mann, S.O.,196831241244McIntosh, F.M., P. Williams, R. Losa, R.J. Wallace, D.A. Beever and C.J. Newbold,20036950115014Molero, R., M. Ibara, C. Caalsamiglia, A. Ferret and R. Losa,200411491104NRC,20017th Edn.,Pages: 405Pages: 405Newbold, C.J., F.M. McIntosh, P. Williams, R. Losa and R.J. Wallace,2004114105112Ogimoto, K. and S. Imai,1981Randhir, S. and K. Pradhan,19811st Edn.,pp: 23pp: 23SAS,199612 Edn., Version 6,Tatsouka, N., K. Hara, K. Mlkuni, K. Hara, H. Hashimoto and H. Itabashi,2008in vitro.]]>796875Tedeschi, L.O., D.G. Fox and T.P. Tylutki,20033215911602Wallace, R.J., N.R. McEwan, F.M. McInotoch, B. Teferedegne and C.J. Newbold,20021014581468Wallace, R.J.,200463621629Wang, Y., T.A. McAllister, L.J. Yanke, Z. Xu, P.R. Cheeke and K.J. Cheng,2000In vitro effects of steroidal saponins from Yucca schidigera extract on rumen microbial protein synthesis and ruminal fermentation.]]>8021142122Weatherburn, M.W.,196739971974Yang, W.Z., C. Benchaar, B.N. Ametaj, A.V. Chaves, M.L. He and T.A. McAllister,20079056715681Zafra, M.A., F. Molina and A. Puerto,20031073744Steel, R.G.D. and J.H. Torrie,1960Bryant, M.P. and L.A. Burkey,195336205217