Bacteriolytic activity of ruminal protozoa is affected by rate and type of common essential oils: Effect of thyme oil

Abstract

Over the past two decades, research into the effects of essential oils (EOs) on rumen microorganisms as an alternative to antibiotics has intensified. Yet, there are few investigations on rumen protozoa. To evaluate if EOs have antiprotozoal efficacy against rumen protozoa, the present investigation was conducted. Using the potentiality of rumen protozoa to digest 14C-labeled bacteria, the influence of EOs on in vitro protozoal activity was determined. For the study, orange peel, cinnamon, laurel, oleaster, garlic, and thyme essential oils were selected. Control (without essential oil), 500 mg/kg, 1000 mg/kg, and 5000 mg/kg dosages were used. Except for garlic oil, all essential oils showed a notable effect on antiprotozoal activity. The highest antiprotozoal impact was reported at 500 mg/kg and 1000 mg/kg doses of thyme oil, with respective reductions of 89.1% and 84.8% in bacteria degraded by protozoa. Cinnamon and oleaster oils had the strongest antiprotozoal efficacy at a concentration of 5000 mg/kg. At 5000 mg/kg doses of oleaster and cinnamon oils, the quantity of 14C-labeled bacteria degraded by protozoa was reduced by 96% compared to the group that served as the control. In conclusion, orange peel, cinnamon, laurel, oleaster, and thyme oils demonstrated remarkable in vitro antiprotozoal activity; however, more comprehensive research is required to analyse the effects of the EOs used in this study on rumen living groups such as protozoa, bacteria, and yeast and on rumen dynamics.

Effects of Garlic Oil and Cinnamaldehyde on Sheep Rumen Fermentation and Microbial Populations in Rusitec Fermenters in Two Different Sampling Periods

“…The abundance of total bacteria in batch cultures, as well as that of protozoa and F. succinogenes in the rumen of steers, were adversely affected by the use of cinnamon EO containing between 57% and 70% of CIN [50,51]. Although these results partially agree with those of the present study, Khorrami et al [49] also reported that supplementing the diet of steers with CIN (5.7 g of cinnamon essential oil/d) decreased the relative abundance of archaea in the rumen. As cinnamon essential oil contains other compounds besides CIN, their combination might have a synergistic effect on certain microbial populations.…”

“…Moreover, Chapman et al [17] observed a reduction in urinary urea N and total purine derivatives after supplementing the diet of dairy cows with 2 mg/kg of BW, without another effect on milk performance and rumen fermentation parameters. Although the effect of CIN on nitrogen metabolism in the rumen is difficult to explain, Sahan [49] studied the influence of cinnamon essential oil on in vitro protozoal activity, determined by the potentiality of rumen protozoa to digest 14C-labeled bacteria, and he observed a lower degradation of bacterial by protozoa after adding a dose of 5000 mg/kg of cinnamon essential oil. The results of this study suggest that CIN supplementation may increase the supply of microbial protein to the host animal, which is a positive and very interesting result.…”