In vitro evaluation of the effects of Ajowan (CarumcopticumL.) essential oils on the parameters of ruminal fermentation

 
Abstract
            The aim of this study was to evaluate the effect of Ajowan essential oils (AEO) on rumen fermentation using in vitro gas production. Therefore, different doses of AEO (i.e., 0, 150, 300, 450 or 600 ppm) were added to the syringes of the gas production. A typical diet of growing lambs was used as fermentation substrate.  At the first step, the gas production syringes were incubated for 144 hours to estimate kinetics of fermentation (i.e., asymptotic gas production, lag time and extent of dry matter degradation). At the second phase, concentration of total volatile fatty acids (TVFA), ammonia, microbial mass and true organic matter digestibility were determined. Inclusion of AEO decreased asymptotic gas production and extent of dry matter degradability. Using AEO at levels of 150 or 300 ppm enhanced microbial mass. Partitioning factor also increased in parallel with the increment of AEO level, whereas true organic matter digestibility declined. Overall, the result of this study showed the antimicrobial activity of AEO against rumen microorganisms. AEO has the potential for modulating rumen fermentation and further research is needed to assess its effect upon microbial biomass and profile of individual fatty acids at lower doses of inclusion.