The Effects of Various Essential Oils of Medical Plant Seeds and Spices on Digestion Characteristics and Population Changes of Ruminal Anaerobic Fungi in <i>in vitro</i> Condition

Abstract

The effect of essential oils (EO) of medical plant seeds and spices on rumen microbial fermentation of alfalfa hay, sugar beet pulp and barley grain (as substrate) were evaluated under <em>in vitro</em> conditions. <em>In vitro</em> incubations were carried out using the gas production method with glass syringes. Treatments were as follows; a control (no additive), monensin, EO of cinnamon, black pepper seed, cumin seed, fennel seed and garlic oil (200 and 400 µL/g DM). Monensin was used as a positive control in the medium at 5 µmol. Data on gas production were fitted using an exponential equation. Results showed that compared to control treatments, monensin had a significant increase on gas production (P<0.05), and cumin seed EO decreased gas production of the feed samples (200 and 400 µL). The effects of treatments on <em>in vitro </em>ruminal fermentation characteristics were tested using an <em>in vitro </em>culture inoculated by mixed rumen microbes. The test treatments were as follows; control (no additive), EO of cinnamon, black pepper seed, cumin seed and fennel seed. Evaluations were made for medium pH, ammonia nitrogen concentration and dry matter disappearance after a 48 h incubation period. To evaluate the effect of EO on <em>in vitro </em>ruminal fungi populations, a sample was taken from the medium after a 120 h incubation period and fungal population was determination by real-time polymerase chain reaction. Compared to the control treatment, cumin and cinnamon additions resulted in a significant decrease (P<0.05) on disappearance of dry matter in the feed samples. In the present study, additions of all tested EO to alfalfa hay treatment showed a significant increase in the final pH of the culture (P<0.05). However, cinnamon addition resulted in a significant decrease in medium ammonia nitrogen concentration for each of the feed samples (P<0.05). Results of the present study also demonstrate that addition all of the tested EO to alfalfa hay had a significantly decrease on <em>in vitro </em>ruminal fungal population (P<0.05).