The effect ofOriganum syriacumL. extract and carvacrol onthe invitro digestion, estimated digestion values, ammonia and organic acid concentrations inthe fermentation fluid oflucerne herbage.

Abstract

The effects induced bymedicinal aromatic plants inbiological systems vary with the type and amount ofbioactive substances these plants contain. Whether the purified form ofthe main chemical components ofthese plants, such ascarvacrol and thymol, orplant volatile oils containing tens ofbioactive compounds are more effective remains aquestion ofdebate. This study was aimed atproviding acomparative assessment ofthe effects ofOriganum syriacumL. (wild mountain thyme) volatile oil (OSVO) and one ofits main components, carvacrol (CRV), onthe invitro ruminal degradability oflucerne herbage and methane production during the degradation oflucerne. For this purpose, wild thyme was harvested atthe beginning ofthe flowering period, and the OSVO was extracted from the plant bysteam distillation. Gas production assays were performed infive groups ofruminal fluid samples, one ofwhich was maintained for control purposes, and the other four 40/60/80mg/l ofOSVOand 60mg/l ofCRV were added. Compared tothe control group, inthe samples with the added CRV and OSVO, theamountsofinvitro total gas and methane production were observed tohave been affected, but nodecrease was detected inthe ruminal protozoa counts. The level ofammonia nitrogen was lowest inthe groups, inwhich CRV and 40mg/l ofOSVO (P< 0.01) were added. The ruminal protozoa counts were not affected bytheaddition ofCRV andOSVO. While the total volatile fatty acid (TVFA) and propionic acid (PA) concentrations intheinvitro fermentation fluid oflucerne herbage were low inall the groups, butyric acid was detected atalevel of40mg/l inthe group where CRV was added. The OSVO was ascertained tohave induced dose-dependent alterationsintheinvestigated invitro digestion parameters. Inresult, CRV (60mg/l) and OSVO (40mg/l) were determined tohave shown arelatively positive effect onthe invitro ruminal gas production. The anti-methanogenic effect ofthe plant extracts was due tothe decreased digestibility ofthe lucerne herbage. This can have apositive impact onthe environment, but thesame cannot besaid for the animal nutrient use and animal performance.