eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2019-06-25 16 2 333 341 10.13005/bbra/2749 33842 article Seyed Masoud Davoodi 1 Mohsen Danesh Mesgaran 1 Ali Reza Vakili 1 Reza Valizadeh 1 Abdollah Ghasemi Pirbalouti 2 Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O. Box 91775-1163, Mashhad, Iran. Department of Medicinial Plants, Faculty of Agriculture, Shahrekord Branch, Islamic Azad University, P.O. Box 166, Shahrekord, Iran. Present study was conducted to investigate the effect of including plant essential oils on in vitro ruminal fermentation and microbial nitrogen synthesis of a dairy cow diet rich in concentrate. The treatments consisted of the diet alone (control; BD) as well as containing 50 and 100 μl L^-1 essential oil of thyme (BDT), mint (BDM), savory (BDS), or a mixture of the essential oils at the rate of 1:1:1 (BD_mix). Essential oils decreased gas production at 24, 48 and 96 h of incubation compared with that of BD. However, mint at the rate of 50 or 100 μl L^-1 resulted an increase in the microbial nitrogen when compared to BD, BDS and BDT. The nitrogen content of truly undegraded residu (NDFN) content and NH3-N concentration were lower, while the dry matter digestibility was greater in the BD_mix, regardless of dosage levels, as compared with the control. The inclusion of a mixture of essential oils at 50 μl L^-1 to the basal diet caused intensified dry matter disappearance, in comparison to other treatments. Results showed  that  the synergetic effects of essential oils together in a dairy cow diet of rich in concentrate can alter rumen microbial fermentation and improve microbial protein yield. https://www.biotech-asia.org/vol16no2/in-vitro-effect-of-essential-oils-on-rumen-fermentation-and-microbial-nitrogen-yield-of-high-concentrate-dairy-cow-diet/ Essential Oils; In Vitro Fermentation; Mint; Microbial Nitrogen; Savory; Thyme