Effect Of Essential Oil On Rumen Fermentation And Methanogenesis In Vitro Method

This study was carried out to investage the effect of plant essential oil with different dose levels onrumen microbial fermentation by3methods of simulating rumen fermentation in vitro, witch objectivewas screening for the effects of plant essential oils on conducive to rumen fermentation or inhibitmethanogenesis.Experiment Ⅰ: An in vitro gas production trial was used to study the effect of tea tree oil,cinnamon oil, and clove bud oil with different dose levels on subsequent72h rumen fermentation andmethanogenesis. The results showed that1) there were no effect on the production of microbial crudeprotein (MCP), but the concentration of ammonia N (NH3-N) were decreased with adding tea tree oiland cinnamon oil, especially adding the cinnamon oil at the dose level of300or1500mg/L(P<0.05).2) the production of total volatile fatty acid (TVFA) and concentration of propionate were decreasedby adding1000mg/L tea tree oil or1500mg/L cinnamon oil. At the does level of50and100mg/L,the tea tree oil increased the concentration of butyrate acid. The production of iso-butyrate andiso-valerate acid were increasing with300and500mg/L cinnamon oil.3) At100mg/L, tea tree oil andclove bud oil were significant differences on the theory maximum gas production. compared with thecontrol groups, All treatments tended to decrease the methane volume fraction (P<0.05).In general,the tea tree oil at the level of100mg/L and cinnamon oil at the100and300mg/L may be allowed tomanipulation of rumen microbial fermentation.Experiment Ⅱ: An in vitro batch fermentation trial was used to study the effect of cinnamonoil and spearmint oil with different dose levels on subsequent72h rumen fermentation and dietdigestibility.1) With prolonging the fermentation time, the concentrations of NH3-N were continue torise by adding0、100and500mg/L cinnamon oil and spearmint oil, and remain unchanged by adding1500mg/L cinnamon oil and spearmint oil, and MCP concentrations decreased and then increased withadding cinnamon oil at the dose level of500and1500mg/L.2) Compared with the control groups,MCP concentrations tended to increase by adding100mg/L spearmint oil, and decreased (P<0.05) byadding1500mg/L spearmint oil. Concentrations of TVFA, propionate and acetate increased (P <0.05)with adding100mg/L spearmint oil at48and72h fermentation, and decreased (P<0.05) by adding500and1500mg/L spearmint oil and cinnamon oil. At the dose level of500and1500mg/L, spearmintoil and cinnamon oil all decreased (P<0.05) the in vitro dry matter digestibility (IVDMD). In general,the addition of spearmint oil and cinnamon oil may be beneficial to manipulate rumen microbialfermentation at the dose level of100mg/L, and harmful to the rumen fermentation at the dose more than500mg/L.Experiment Ⅲ: A dual flow continuous culture system was used to evaluate the effect of plantessential oil with different dose levels on rumen microbial fermentation and methanogenesis. Twelvefermentors were randomly allocated to4groups, and witch were add0,100,500and1500mg/L ofcinnamon oil or spearmint oil respectively. Compared with the control groups,1)the addition ofcinnamon oil at a level of1500mg/L decreased in pH, digestibility of neutral detergent fbre(dNDF),acid detergent fber(dADF) and crude protein(dCP)(P<0.05).2)There were no effect on theconcentration of volatile fatty acid and acetate/propionate ratios(A/P)with adding cinnamon oil orspearmint oil at the dose level of100mg/L(P＞0.05). Concentrations of TVFA, acetate and propionatewere decreased (P<0.05) with adding cinnamon oil of500mg/L at fermentation27and99h, and1500mg/L at all the fermentation time. With prolonging the fermentation time, concentrations of TVFA,acetate and propionate were decreased (P<0.05), and A/P was increased(P<0.05)with adding cinnamonoil at the dose level of1500mg/L.3)The addition of cinnamon oil or spearmint oil with a level of1500mg/L and cinnamon oil with a level of500mg/L decreased (P<0.05)protozoa number. Alltreatment groups decreased (P<0.05)the methane volume fraction compared with the control groups. Itis concluded that the addition of cinnamon oil or spearmint oil at the level of100mg/L may bebeneficial to manipulate rumen microbial fermentation.