Effect of Cyclotrichium niveum Essential Oil on Rumen Microbial Fermentation and in vitro Digestibility of Barley

Abstract

The digestibility of feed in ruminants and the volatile fatty acids (VFA) resulting from digestion directly affect animal performance. It has long been studied on the use of essential oils as an alternative to antibiotics to ensure optimum conditions for the rumen environment. Cyclotrichium niveum (mountain mint) essential oil is rich in antimicrobial agents. In this study different doses (0, 50, 100 and 150 mg/L of culture fluid) of Cyclotrichium niveum essential oil was incubated 24 hours with barley in diluted ruminal fluid takes from fistulated cows fed with a 40:60 concentrate:forage diet in order to assess the effects on rumen microbial fermentation and in vitro true digestibility of barley. True digestibility of barley was determined in ANKOM Daisy Incubator. All doses of Cyclotrichium niveum significantly (P<0.001) decreased the in vitro dry matter (DM), organic matter (OM), neutral detergent fiber (NDF) digestibility of barley. Cyclotrichium niveum essential oil negatively affected end-products of rumen fermentation; the value of the measured rumen volatile fatty acids (VFA: acetate, propionate, butyrate, isobutyric acid, valerate and isovalerate) significantly decreased compared to the control group (P<0.001). Carbon dioxide and methane gases created as a result of incubation in rumen fluid were calculated using volatile fatty acid values formed in rumen fluid. The addition of Cyclotrichium niveum essential oil significantly reduces the CO2 in rumen fluid (P<0.001). Methane (CH4) gas from rumen fluid was significantly decreased in treatment groups compared the control group (P <0.001) While end-products of rumen fermentation parameters significantly decreased with all doses of Cyclotrichium niveum essential oil, rumen pH has increased (P<0.05). The results show that when the Cyclotrichium niveum essential oil incubated with barley significantly inhibited the rumen microbial activity and overall fermentation process of rumen.