Thymus kotschyanus Essential Oil Components and Their Effects on in vitro Rumen Fermentation, Protozoal Population and Acidosis Parameters

This study aimed to identify chemical composition of Thymus kotschyanus essential oil (TKEO) and to evaluate the effects of different doses of TKEO on in vitro gas production, fermentation parameters, acidosis and protozoal population using a completely randomized design with four replicates. Two diets (D1: 100% forage and D2: 30% forage+70% concentrate) were incubated with buffered rumen fluid as fermentation substrates. The plant materials were dried and hydrodistilled in order to obtain their essential oil (EO). The essential oil was analyzed by capillary GC/MS. Gas production (GP144 h) was recorded up to 144 h of incubation. After 24 h, the parameters of apparent in vitro dry matter digestibility (AIVDMD), true in vitro dry matter digestibility (TIVDMD), organic matter digestibility (OMD), partitioning factor (PF) and microbial biomass (MB) were estimated. The main components of TKEO were 25.77% geraniol and 14.85% thymol. Asymptotic GP144 h decreased by TKEO. Addition of TKEO also decreased GP24 h, AIVDMD, TIVDMD and OMD. However, PF and MB increased. Acidosis test was not affected by EO. Inclusion of TKEO decreased the total number of protozoal population. These results indicated that TKEO could potentially be used to modulate rumen fermentation therefore further in vivo research is needed to determine the optimal doses.