Laboratory study of Balangu (Lallemantia royleana) essential oil effects on gas production kinetic, degradability, protozoan population, and some fermentation parameters of a balanced diet

Results and discussion: No changes were observed in the concentration of ammonia nitrogen and protozoal population of the culture medium due to the addition of LREO, but pH (linear, P=0.02) and TVFA significantly decreased and increased, respectively compared with the control group. With increasing LREO in the culture medium, most gas production parameters (potential gas production and gas production at 12, 24, 48, and 72 h of incubation) significantly increased as linear and quadratic; however, methane emissions did not change. Although IVDMDandIVOMD showed a significant increase (linear and quadratic) due to the addition of LREO; in contrast, the PF, MMY, and EMMS significantly decreased (linear and quadratic) compared with the control group. Supplementation of 5 mg/l of some essential oils increased by 8% the concentration of total VFA (Castillejos et al. 2007). Evans and Martin (2000) reported that thymol (400 mg/l) decreased the total VFA concentration, suggesting that the used dose was toxic to rumen bacteria. Previous studies (Molero et al. 2004 and Newbold et al. 2004) demonstrated that a blend of essential oils inhibited proteolysis and amino acid deamination. Recent studies showed that most essential oils tested at high concentrations (i.e., 3000 and 5000 mg/l) inhibited rumen microbial fermentation and reduced total VFA concentration, which demonstrates their antimicrobial activity (Cardozo et al. 2005, Busquet et al. 2006, Castillejos et al. 2006 ). Conclusion: The overall results showed that LREO can alter the fermentation pattern in the medium by improving some of the parameters (increasing in gas yield, TVFA, IVDMD, and IVOMD), and it seems that the level of 450 mg of LREO/L has more effect on these parameters. The addition of LREO can also decrease the microbial mass yield in the rumen, modify the production of VFA without any change in ammonia nitrogen. Effects of LREO on in vivo rumen fermentation and animal performance require further researches.